How to Make the Best Classic Italian Tiramisu

Preparing the Mascarpone Filling

1. Place the sugar and the egg yolks in a medium-sized glass bowl. 
2. Set the bowl over a saucepan of gently simmering water. The water should not touch the bottom of the bowl. 
3. Whisk the sugar and egg yolks vigorously for about 3 minutes or until they doubled the size and the mixture is foamy and light. I recommend using a hand mixer for this step. 
4. Remove the bowl from the heat, continue whisking the egg yolk mixture for another few minutes, and let it cool down to room temperature. 
5. Add the mascarpone cheese to the egg yolk mixture one spoonful at a time and gently fold it in using a hand whisk. Don't use an electric hand mixer to avoid over-whipping the mascarpone cheese. Set it aside.
6. Whisk the double cream in a separate bowl until it holds stiff peaks and add it to the egg yolk-sugar-mascarpone mixture.
7. Gently fold them together using a silicon spatula. Incorporate the mascarpone mixture with the whipped cream, rather than stirring it to help prevent the mixture from separating and becoming grainy.
8. In a separate bowl, whip the egg whites with cream of tartar until stiff. Make sure the bowl is dry and clean and there isn't any trace of egg yolk in the whites.
9. Add the stiffened egg whites to the mascarpone mixture, and mix with a silicon spatula, from bottom to top. Mix slowly until it’s smooth and creamy. 

Building the Tiramisu

1. When the mascarpone filling is ready, mix the strong espresso with 2 tablespoon rum, brandy, or coffee liquor in a bowl.
2. Quickly dip the ladyfingers into the coffee mixture and arrange half of them on the bottom of a 14" x 9.5" (30cm x 20cm) rectangular ceramic or glass dish.
3. Spoon half of the mascarpone filling over the first layer of ladyfingers and spread evenly.
4. Dip the remaining ladyfingers very quickly into the coffee mixture and arrange a second layer over the mascarpone filling.
5. Spoon the remaining mascarpone mixture over the ladyfingers and spread evenly.
6. Sprinkle with cacao powder, cover with cling film and let it rest in the fridge overnight or 10-12 hours before serving.