Classic Coffee-Flavored Tiramisu with Cooked Egg Cream

Method

1. In a shallow bowl, mix the room-temperature espresso with 3 tablespoons of rum. Working one at a time, quickly dip both sides of half the ladyfingers into the mixture—just enough to moisten, not soak. Arrange them in a single layer on the bottom of a 9×13-inch baking dish.
2. In a heatproof bowl (preferably metal or glass), whisk together the egg yolks and sugar. Set the bowl over a saucepan of simmering water, making sure the bottom does not touch the water. Whisk constantly for 10–12 minutes until the mixture reaches 160°F on an instant-read thermometer; it will become lighter in color, slightly thickened, smooth, and no longer gritty when rubbed between your fingers. Remove from heat and continue whisking for a couple of minutes to cool slightly. Set aside.
3. In a large mixing bowl, beat the cold mascarpone with the remaining 3 tablespoons of rum until smooth. Using an electric hand mixer, gradually beat in the warm yolk mixture until fully combined and creamy.
4. In a separate chilled bowl, beat the cold heavy cream with clean beaters until stiff peaks form. Be careful not to overbeat. With a rubber spatula, gently fold half of the whipped cream into the mascarpone mixture, then fold in the remaining half just until no streaks remain. Do not overfold.
5. Spread half of the cream evenly over the first layer of ladyfingers. Quickly dip the remaining ladyfingers one by one into the espresso mixture and arrange them on top. Spread the remaining cream over the second layer. Cover the dish tightly with foil and refrigerate for at least 8 hours, or overnight. Before serving, dust generously with cocoa powder through a fine sieve.