Step 1
In a large heatproof bowl, combine egg yolks, ¼-cup sugar, and salt. Set the bowl over a saucepan of simmering water. Whisk the mixture until the sugar dissolves and the egg yolks turn to a light-pale yellow color. About 5-6 minutes. Remove from heat and set aside. Allow the mixture to cool. Stir occasionally.
Step 2
In the bowl of an electric mixer fitted with the whip attachment, whip the cream and the rest of the sugar (1/2-cup) until soft peaks form. Add vanilla and mascarpone cheese and continue whipping at medium speed until stiff peaks form.
Step 3
Fold the mascarpone mixture with the cool egg yolk mixture until combined and smooth.
Step 4
In a shallow dish, mix espresso with rum.
Step 5
Assemble. Dip ladyfingers, one at a time in the coffee mixture. Arrange in a single layer on the bottom of an 8in x 8in x 2in pan. Spread half of the mascarpone cream on top. Dust half of the cocoa powder over it. Repeat process for a second layer of ladyfingers, cream and cocoa.
Step 6
Refrigerate for at least 4 hours or overnight.
To make a 3-layer tiramisu, use the same amount of ingredients but use a loaf pan to assemble the cake.
