Tiramisu

Brew 300ml strong espresso, set aside to cool to room temperature (approximately 20 minutes), then stir in optional 30ml dark rum if using. Pour the mixture into a shallow dish wide enough to lay a ladyfinger flat, and set aside. Never use hot coffee for soaking, as it will turn ladyfingers overly mushy and cause the cream to melt during assembly.

Fill a small saucepan with 5cm of tap water, bring to a gentle simmer over medium-low heat (do not bring to a rolling boil). Set a heatproof glass bowl over the pan, ensuring the bottom of the bowl does not touch the simmering water. Add 4 pasteurized egg yolks and 80g granulated sugar to the bowl, then whisk continuously for 6-8 minutes until the mixture is pale lemon-yellow, thick, tripled in volume, and reaches a food-safe temperature of 71°C (160°F). Remove the bowl from the heat immediately.

Let the cooked yolk mixture cool for 10 minutes, then add 500g room-temperature mascarpone cheese and 1 teaspoon vanilla extract. Use a flexible silicone spatula to fold the mixture in a gentle figure-8 motion until completely smooth with no visible lumps. Do not overmix, as aggressive stirring can cause mascarpone to separate and create a watery final texture.

In a pre-chilled stainless steel mixing bowl, pour 240ml of cold heavy whipping cream. Use an electric hand mixer set to medium speed to whip the cream for 2-3 minutes, until soft, billowy peaks form (the tips of the peaks will curl over when the mixer is lifted straight up). Do not whip to stiff, dry peaks, as this will create a grainy, uneven texture in the final tiramisu.

Add one-third of the whipped cream to the mascarpone base, folding gently to lighten the dense mixture, then add the remaining whipped cream in two equal batches. Fold slowly and carefully until the mixture is uniform in color with no white streaks remaining. Avoid vigorous stirring, as this will deflate the air in the whipped cream and create a dense, heavy dessert.

Working one at a time, quickly dip each ladyfinger into the cooled coffee mixture for 1-2 seconds per side (do not soak longer, as ladyfingers will become soggy). Arrange a tight, single layer of dipped ladyfingers across the bottom of a 20cm (8-inch) square glass baking dish. Spread half of the mascarpone cream evenly over the ladyfinger layer, smoothing with an offset spatula. Repeat with a second layer of coffee-dipped ladyfingers, then top with the remaining half of the cream, smoothing the top surface to a flat, even finish.

Cover the baking dish tightly with plastic wrap, then refrigerate for a minimum of 4 hours (preferably 8-12 hours overnight) to allow the flavors to meld and the cream to set fully. Right before serving, place 2 tablespoons of unsweetened cocoa powder in a fine-mesh sieve, and dust a thin, even layer over the entire top of the tiramisu. Add dark chocolate shavings as an optional garnish if desired.