How to Make It
In a medium bowl, beat the mascarpone with the egg yolks and 3 tablespoons of the sugar. In a large stainless steel bowl, whip the egg whites until they hold soft peaks. Add the remaining 1 tablespoon of sugar and beat until the peaks are firm and glossy. Fold half of the egg whites into the mascarpone, then fold in the remaining whites.
Pour the coffee into a deep dish. Dip both sides of 12 of the ladyfingers into the coffee and arrange them in a single layer in a deep 8-inch-square glass baking dish. Spread half of the mascarpone filling on top. Dip the remaining 12 ladyfingers in the coffee and arrange them in a layer over the filling. Spread the remaining mascarpone over the lady-fingers and dust generously with cocoa. Refrigerate the tiramisu until thoroughly chilled, at least 2 hours or overnight.
Please be aware that this recipe uses raw eggs.