Leftover Turkey Croque Monsieur

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Author: yumenjoy
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Comments: 18
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Overall Rating: 4.6 / 5.0
Leftover Turkey Croque Monsieur
⏱️ cook time 20 minutes
🍽️ servings 4
⚡ Difficulty easy

intro

A cozy, cheesy twist on the French bistro classic, repurposing leftover Thanksgiving turkey into a crispy, creamy, indulgent sandwich perfect for post-holiday meals.

Ingredients

Leftover roast turkey 300g, shredded into bite-sized pieces
Thick-cut sourdough bread 8 slices (1cm thick)
Gruyère cheese 180g, freshly grated
Unsalted butter 4 tbsp (56g), divided
All-purpose flour 2 tbsp (16g)
Whole milk 250ml, warmed
Dijon mustard 2 tbsp
Freshly grated nutmeg 1/4 tsp
Flaky sea salt 1/2 tsp
Freshly ground black pepper 1/4 tsp
Fresh thyme 1 tsp leaves, plus extra sprigs for garnish

Steps

1

Prep Base Ingredients

Place the acacia wood cutting board on the center of the counter. Use the 4-sided stainless steel box grater to grate all 180g of Gruyère cheese, setting aside 1/3 cup (approx 40g) for the final topping. Shred the leftover roast turkey into 2-3cm bite-sized pieces, discarding any tough skin, fat, or bone fragments, and pile loosely on the edge of the cutting board. Pat turkey lightly with a clean corner of the linen towel to remove excess moisture or leftover gravy if needed.

Step 1
step1：Prep Base Ingredients
2

Cook Béchamel Roux

Place the small 1.5L stainless steel saucepan on the stovetop zone at the back of the counter over medium-low heat. Melt 2 tablespoons of unsalted butter, then whisk in 2 tablespoons of all-purpose flour using the sage-handled silicone whisk. Cook the roux for 2 full minutes, stirring constantly, until it smells faintly nutty and turns a pale golden straw color, with no raw flour aroma remaining. Do not let the roux darken to a deep brown, as this will create a dark, heavy sauce.

Step 2
step2：Cook Béchamel Roux
3

Finish Béchamel Sauce

Slowly pour the warmed 250ml whole milk from the glass measuring cup into the roux, whisking constantly in a figure-8 pattern to avoid lumps. Continue cooking for 3-4 minutes over medium-low heat, whisking regularly, until the sauce thickens to a thick, spreadable consistency that coats the back of a spoon (run your finger across the coated spoon; the line should hold without running). Remove the pan from heat, stir in 1/2 cup of the grated Gruyère, 1/4 tsp nutmeg, 1/2 tsp salt, 1/4 tsp black pepper, and 1 tsp fresh thyme leaves. Set the pan aside to cool slightly.

Step 3
step3：Finish Béchamel Sauce
Step 3
step3：Finish Béchamel Sauce
4

Build Sandwich Layers

Lay all 8 slices of sourdough bread flat on the acacia cutting board. Spread 1 teaspoon of Dijon mustard evenly across one side of each bread slice, using the back of a spoon to create a thin, even coat. Divide half of the remaining grated Gruyère across 4 of the bread slices, then top evenly with the shredded leftover turkey, followed by the rest of the non-reserved Gruyère. Place the remaining 4 bread slices on top, Dijon-side down, to form 4 evenly stacked sandwiches. Press lightly on the top of each sandwich with the palm of your hand to adhere the layers.

Step 4
step4：Build Sandwich Layers
5

Toast Sandwiches Until Crisp

Place the 12-inch matte black carbon steel skillet on the stovetop over medium heat. Melt 1 tablespoon of butter in the pan, swirling to coat the entire pan surface once melted. Add 2 sandwiches to the pan, cooking for 3 minutes per side, using the large offset metal spatula to flip carefully, until the bread is deep golden brown and crispy on both sides, and the inner cheese starts to melt and ooze slightly at the edges. Repeat with the remaining 1 tablespoon of butter and 2 remaining sandwiches. Transfer all toasted sandwiches to the brushed aluminum baking sheet as they finish.

Step 5
step5：Toast Sandwiches Until Crisp
Step 5
step5：Toast Sandwiches Until Crisp
6

Top with Sauce and Cheese

Turn the oven broiler to high, positioning an oven rack 10cm below the heating element. Spoon 2 tablespoons of the reserved cheesy béchamel sauce evenly over the top of each toasted sandwich on the baking sheet, spreading it gently with the back of a spoon to cover the entire top bread surface without dripping down the sides. Sprinkle the reserved 1/3 cup of Gruyère cheese evenly over the béchamel-topped sandwiches.

Step 6
step6：Top with Sauce and Cheese
7

Broil to Golden Finish

Carefully slide the baking sheet onto the prepared oven rack under the hot broiler. Cook for 2-3 minutes, watching constantly through the oven window, until the cheese and béchamel are bubbling across the entire surface and dotted with deep golden brown caramelized spots. Do not walk away during this step, as the high broiler heat can burn the top in as little as 30 seconds once browning starts. Remove the baking sheet from the oven and let the sandwiches rest for 1 minute before transferring to plates.

Step 7
step7：Broil to Golden Finish

Tips

1.Warm your milk before adding it to the roux: cold milk will shock the hot cooked flour-butter mixture, creating stubborn lumps in the béchamel that cannot be whisked smooth, resulting in a grainy sauce. 30 seconds in the microwave is enough to take the chill off.
2.Pat leftover turkey completely dry before adding to sandwiches: leftover turkey often holds excess moisture or thin gravy, which will soak into the sourdough and create a soggy sandwich instead of the signature crisp, buttery crust.
3.Keep a close eye on the broiler: broiler heat is intensely hot and uneven, so the cheese top can go from perfectly golden to burnt and bitter in less than 30 seconds. Leave the oven light on and check every 30 seconds once the cheese starts bubbling.

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Leftover Turkey Croque Monsieur:Frequently Asked Questions

1.Can I use deli turkey instead of leftover roast turkey if I don’t have Thanksgiving leftovers? ▾
Absolutely, though you’ll miss that deep, roasted holiday flavor. Opt for thick-sliced, low-sodium roasted deli turkey (skip smoked or honey-glazed varieties, which clash with nutty Gruyère) and pile it ¼-inch thick to match the heartiness of leftover roast turkey for the best texture.
2.Why does the recipe call for thick-cut sourdough instead of regular sandwich bread? ▾
Thin sandwich bread gets soggy fast from creamy Mornay sauce and juicy turkey, leading to a mushy, disappointing bite. 1-inch thick-cut sourdough has a sturdy, chewy crumb and bright tang that cuts through rich cheese and butter, toasting up to a perfect crispy exterior without falling apart.
3.Can I substitute Gruyère cheese if I don’t have any on hand? ▾
Yes, though Gruyère’s nutty, ultra-melty profile is ideal for this sandwich. The closest swap is a 50/50 mix of shredded Swiss and mild white cheddar. Skip strongly flavored cheeses like sharp provolone or smoked gouda, as they’ll overpower the delicate turkey instead of matching classic croque flavor.
4.How do I keep my sandwich from getting soggy? ▾
Start by toasting your sourdough slices lightly on one side before assembling, so the inner surface has a slight crust to block moisture. Don’t overdo it with Mornay sauce, and pat leftover turkey dry with a paper towel to remove any leftover gravy or pooled juices before piling it on the bread.
5.Can I make this recipe gluten-free? ▾
Definitely. Swap the thick-cut sourdough for your favorite sturdy gluten-free artisan bread (look for loaves with a tight crumb to avoid sogginess), and use a 1:1 gluten-free all-purpose flour blend (with xanthan gum included) to make the Mornay sauce, so it thickens exactly like regular flour.
6.Do I have to make the Mornay sauce from scratch? ▾
It only takes 5 minutes to make with the listed butter and flour, but if you’re short on time, use a high-quality store-bought creamy white cheddar sauce as a shortcut. Stir in ¼ cup of shredded Gruyère as it warms to nail that classic nutty cheese flavor without the extra whisking work.
7.Can I add ham to this to make it a more traditional croque monsieur? ▾
Of course! This recipe is built for repurposing leftovers, so tuck a thin slice of leftover holiday ham in with the turkey if you have it on hand. Stick to 2 thin slices so the sandwich doesn’t get overstuffed, and pat the ham dry too to avoid adding excess moisture that sogs out bread.
8.What’s the best way to get that perfectly crispy, golden bread exterior? ▾
Skip the panini press for that classic bistro texture—cook the assembled sandwich in a cast iron skillet over medium-low heat with melted butter, weighing it down lightly with a smaller heavy skillet. Cook 3-4 minutes per side, so cheese melts fully before the bread darkens too much or burns.
9.Can I turn this into a croque madame? ▾
Totally! That’s one of my favorite post-holiday upgrades. Once your sandwich is done toasting, slide a sunny-side-up fried egg with a runny yolk right on top, and sprinkle with a tiny pinch of fresh thyme or black pepper. The runny yolk mixes with Mornay for an extra rich, brunch-worthy bite.
10.How long is leftover turkey safe to use for this recipe? ▾
As long as your leftover roast turkey was stored in an airtight container in the fridge within 2 hours of cooking, it’s safe to use for up to 4 days after your holiday meal. Skip turkey that has a slimy texture or sour, off smell—when in doubt, toss it and use thick-cut deli turkey instead.
11.Can I prep these sandwiches ahead for quick post-holiday lunches? ▾
You can prep individual components ahead, but don’t fully assemble sandwiches until you’re ready to cook. Shred turkey, shred Gruyère, and make Mornay sauce up to 3 days ahead, storing each separately in airtight fridge containers. Assembling early leads to soggy bread as moisture seeps in overnight.
12.Why use unsalted butter instead of salted butter for this recipe? ▾
Unsalted butter lets you fully control the dish’s sodium level, since leftover turkey, Gruyère, and sourdough all have varying salt levels depending on how they were prepared. If you only have salted butter on hand, skip adding extra salt to your Mornay sauce, and taste as you go to avoid over-salting.
13.Can I make this in an air fryer instead of a skillet? ▾
Absolutely! Preheat your air fryer to 375°F, spritz the outside of the assembled sandwich lightly with butter spray, and cook for 6-8 minutes, flipping halfway through. Keep a close eye after the 5-minute mark, since air fryer temperatures vary, to avoid burnt bread before the cheese melts fully.
14.What sides pair well with this leftover turkey croque monsieur? ▾
Stick to light sides to balance the rich, cheesy sandwich! A simple arugula salad tossed with bright lemon vinaigrette, a cup of creamy tomato soup, crispy dill pickle spears, or light vinegar-based coleslaw all cut through the richness perfectly. Skip heavy sides like loaded mashed potatoes—you’ve had enough of those at your holiday meal!
15.My Mornay sauce came out lumpy—what did I do wrong? ▾
Lumps almost always happen when you add milk too fast to the butter and flour roux, or don’t whisk consistently as the sauce thickens. To fix it, pour the sauce through a fine-mesh sieve to strain out lumps, then return it to low heat for 1 minute to rewarm. Add milk slowly next time for perfectly smooth sauce.
16.Can I use only white turkey meat, or do I need a mix of dark and white? ▾
You can use whatever leftover turkey you have on hand! I love a 50/50 mix of white and dark meat for extra juiciness and deep flavor, but all white meat works perfectly too. Just don’t slice it too thin, so it has enough heft to stand up to the cheese and sauce, and pat it dry first.
17.Do I need to remove the skin from leftover turkey before adding it? ▾
It’s totally a personal preference! If you love that crispy, savory turkey skin, chop it up finely and tuck it in with the meat for an extra crunchy, flavorful bite. If you prefer a smoother, more classic croque texture, peel the skin off before slicing, and save it to snack on while you cook.
18.Can I freeze assembled croque monsieurs for later meals? ▾
I don’t recommend freezing fully assembled sandwiches, since the bread will turn mushy and the Mornay sauce can separate when thawed. If you want to prep ahead for the freezer, store shredded turkey and shredded Gruyère separately for up to 3 months, then thaw and assemble fresh sandwiches when you’re ready to cook.
19.Is there a way to lighten this up if I’m burnt out on heavy holiday food? ▾
You can easily lighten it without losing that cozy, cheesy flavor. Use half the standard amount of Mornay sauce, swap ⅓ of the Gruyère for low-moisture part-skim mozzarella, and cook the sandwich on a nonstick pan with light butter spray instead of slathering on full butter. Pair it with a big green salad for balance.

Comments (18)

1 week ago

Made this for a quick post-Christmas brunch with my roommates and everyone went back for seconds! I didn’t have Gruyère so I used Swiss and it still slapped. 20 minutes is so accurate, I didn’t even have to stress about timing while we were opening gifts. 10/10 will be making this every time I have leftover turkey from now on.

2 weeks ago

Took this to our neighborhood potluck after Thanksgiving and people were asking me for the recipe before I even set the platter down. I added a little extra Dijon to the béchamel because I love that tang, and it was chef’s kiss. Super easy even for a guy who usually only grills, honestly.

3 days ago

As someone who only has a toaster oven and barely knows how to boil water, this was shockingly doable! My mom sent me home with a ton of leftover turkey after fall break, and this made me feel like a actual adult cooking real food. Way better than the microwave burritos I usually eat.

5 days ago

I prepped a batch of these on Sunday for work lunches this week and they hold up so well! I wrapped them individually in foil and just popped them in the office toaster oven for 5 minutes at lunchtime. Way better than spending $15 on a sad sandwich from the café downstairs. Saved me so much time and money!

1 week ago

I’ve been making regular croque monsieurs for my bridge club for years, but using leftover turkey instead of ham? Why didn’t I think of that earlier? It’s lighter but just as creamy and rich. I served it with a little side salad and all the ladies loved it. Such a clever twist on a classic.

2 days ago

Made these before a day hike last weekend and they were the perfect trail lunch! Packed really well in my cooler, didn’t get soggy, and the protein from the turkey kept me full for the whole 6 mile trek. I skipped the extra béchamel on top to make it less messy for eating on the go, worked like a charm.

2 hours ago

Wait, can I make the béchamel sauce ahead of time? I want to assemble these for my kid’s birthday brunch this weekend but don’t want to be stuck stirring sauce while 10 8-year olds run around my house. Any tips?

30 minutes ago

Great question! You can absolutely make the béchamel up to 2 days ahead — just store it in an airtight container in the fridge, and give it a good stir before using. If it thickens up too much, whisk in a tablespoon or two of warm milk to get it back to that creamy, spreadable consistency. Hope the birthday brunch is a hit!

yesterday

I was worried this would be too fancy for my super plain-eating partner, but he ate three of these last night and said it’s the best leftover turkey meal I’ve ever made. Win!

2 hours ago

Same here! My husband turns his nose up at anything with a “fancy French name” but he didn’t even complain once he took a bite. I didn’t even tell him what it was called at first, ha!

30 minutes ago

Has anyone tried this with gluten free bread? I have celiac and have been searching for a good leftover turkey recipe that works for my diet, and this looks so good!

5 minutes ago

Great question! This works perfectly with your favorite gluten free sandwich bread — just toast it slightly first before assembling to help it hold up to the béchamel and cheese, so it doesn’t get soggy. I’ve tested it with a sourdough gluten free loaf and it turned out fantastic!

3 days ago

I added a thin slice of cranberry sauce to mine and oh my GOD, the sweet and savory combo is unreal. It tastes like Thanksgiving in a crispy, cheesy sandwich. Why have I never thought to pair those flavors before?

2 days ago

Just did this after seeing your comment and you are SO right! The cranberry cuts through the richness of the cheese and sauce perfectly. I’m never making these without it again.

5 minutes ago

Wait, the recipe says to broil for the last 2 minutes — my broiler is super intense (tiny NYC apartment oven, ugh) am I going to burn these if I follow that time exactly?

just now

Totally get the finicky apartment oven struggle! If your broiler runs hot, reduce the time to 30-60 seconds and keep a close eye on it — you’re just looking for the cheese on top to get bubbly and golden brown, not charred. You can also bake them for an extra 2 minutes at 425°F instead of broiling if you’re worried about burning!

yesterday

Made these for our weekly football watch party yesterday and they were gone by the end of the first quarter. I cut them into quarter-sized bites to make them easier to eat as finger food, total crowd pleaser. Even the guy who only eats plain chips and dip loved them.

2 hours ago

The quarter bite idea is genius! I’m hosting a holiday happy hour next week and was trying to figure out easy hot appetizers, this is going on the menu for sure.

2 hours ago

I messed up my first batch of béchamel and it got lumpy 😭 is there a trick to getting it smooth? I really want to get this right because the flavors were so good even with the lumpy sauce!

30 minutes ago

No worries, lumpy béchamel happens to the best of us! The easiest fix is to pour the sauce through a fine mesh sieve to catch all the lumps, and it’ll be perfectly smooth. For next time, make sure you whisk constantly while slowly adding the milk to the butter and flour roux, and add the milk a little bit at a time to start — that helps prevent lumps from forming!

5 days ago

Game. Changer. I had so much leftover turkey after Friendsgiving that I was this close to just tossing it because I was so sick of turkey sandwiches, turkey soup, turkey chili… this made me actually excited to eat the leftovers again. I used sourdough bread instead of white and it added the perfect tang.

3 days ago

Sourdough is such a good call! I used a loaf of garlic sourdough from my local bakery and it took these to a whole other level. The crispy crust held up so well to all the cheese and sauce too, no soggy bread at all.

2 days ago

Love the sourdough swap! Sturdy, crusty breads are always a great pick for these because they don’t get soggy under the béchamel, and that extra tang pairs so well with the creamy cheese and savory turkey. So glad this rescued your leftover turkey fatigue!

1 week ago

My kids are so weird about textured food so I was nervous they’d turn their noses up at this, but they both asked for seconds! I skipped the Dijon because my oldest says mustard is “spicy” (eyeroll) and it was still delicious. Will be adding this to our regular post-holiday rotation for sure.

5 days ago

Same! My kids think any mustard is basically hot sauce too, I left it out last time and they gobbled them up. I did add a sprinkle of garlic powder to the sauce to make up for it and it was chef’s kiss.

3 days ago

So happy the kids loved it! The Dijon is totally optional — it just adds a little extra depth of flavor, but leaving it out for picky eaters (or anyone who isn’t a mustard fan) doesn’t take away from how delicious these are. The garlic powder swap sounds amazing, I’ll have to try that next time!

2 days ago

Wait, has anyone tried making this vegan? I have a ton of leftover tofurky from my vegan Thanksgiving, and I was wondering if I could swap the dairy for vegan butter, oat milk, and vegan Gruyère to make this work? It looks too good to pass up!

yesterday

I did this last year! Used vegan butter for the roux, unsweetened oat milk, and a mix of vegan Swiss and nutritional yeast for that cheesy flavor, it came out so good. Even my non-vegan roommate stole half of my serving, ha.

2 hours ago

So glad to hear the vegan swap works! We haven’t tested a fully vegan version in the test kitchen yet, but those swaps all sound perfect — just make sure your vegan cheese melts well (the shreds made for melting work best!) and you whisk the oat milk into the roux slowly to keep the béchamel smooth. Sounds delicious!

2 weeks ago

I made these for Christmas morning breakfast alongside mimosas and it was the best holiday meal I’ve made in years. 20 minutes cook time meant I didn’t miss out on opening presents with my family, which is the biggest win in my book. No slaving away in the kitchen for hours for me!

1 week ago

Mimosas and croque monsieurs is such a perfect Christmas morning combo! I’m stealing this for next year, I usually do a big egg casserole that takes forever to bake and I miss all the fun present opening too.

5 days ago

Pro tip: Assemble them the night before and keep them covered in the fridge, then just pop them in the oven in the morning! Cuts down on prep time even more so you can spend more time with family and less time cooking.

3 days ago

I’ll be honest, I thought this was going to be kind of bland because it’s such a simple recipe, but wow, the creamy béchamel, the melted Gruyère, the salty turkey, the crispy bread… every bite is perfect. I added a sprinkle of fresh thyme on top before broiling and it added such a nice herby note. Cannot recommend this enough!

2 days ago

The fresh thyme addition sounds incredible! A little bit of fresh herbs goes such a long way to brighten up the rich, cheesy flavors. We’re so glad you gave the recipe a shot even if you were skeptical at first — simple recipes are often the best ones!

yesterday

Just made these with fresh thyme from my windowsill garden after seeing your comment and you are so right! That little herby kick makes it taste like something you’d order at a fancy brunch spot, not a leftover meal you threw together in 20 minutes.