Pour 1-inch of water into a small saucepan and bring it to a boil.
Whisk egg yolks and sugar in a mixing bowl and place on top of the saucepan to make a double broiler. Whisk constantly to cook the egg yolks for about 10 minutes. The egg yolks will increase in volume and lighten in colour. Remove it from the heat and whisk until it has cooled to room temperature.
Stir the room temperature mascarpone cheese into the egg yolk mixture and set aside.
Whip the egg whites until they reach stiff peaks. Gently fold the egg whites into the egg yolk/mascarpone cheese mixture. Cover and refrigerate until ready to make tiramisu.
Mix coffee and liquor in a bowl. Quickly dip ladyfingers into the coffee. You do not want them to soak because they will get too soggy. You could also brush the coffee onto the ladyfingers to have more control.
Arrange ladyfingers into the bottom of a 9x9" baking dish. Top with a layer of the filling. Place another layer of ladyfingers on top of the filling, and then add a final layer of more filling. Finely grate chocolate over top, cover and store in the refrigerator for at least 6 hours to firm up.
Cover and store in the refrigerator for up to 3 days.
Brush the coffee mixture on to the ladyfingers instead of dipping them in. Soggy ladyfingers will ruin the dessert.
Only use Savoiardi Italian ladyfingers in this recipe. Cake style ladyfingers will get too soft.
Can't find ladyfingers in the store? Make your own! My ladyfingers recipe will make the amount you need for this tiramisu recipe.
Have the eggs and mascarpone cheese at room temperature so they mix in smoothly.
You can use 1-2 tablespoons of cocoa powder instead of semi-sweet chocolate.
Let the tiramisu sit in the refrigerator for at least 6 hours before serving.