The Essentials of Classic Italian Cooking by Marcella Hazan
1 1/4 cups strong espresso (find espresso, strong coffee doesn’t really cut it)
5 Tbsp rum (I used brandy- it’s just what I had)
5 tsp sugar
5 Tbsp water
16 ounces pound cake, cut into 1/4″ slices
4 large eggs, separated
1 tsp sugar
6 oz. semisweet chocolate coarsely chopped (or in convenient chocolate chip form)
Whipped cream and fresh fruit (optional)
In a small bowl, combine the espresso, rum, sugar, and water. Moisten a sheet of cheesecloth large enough to line a 9x5x3 inch loaf pan with plenty of overhang. Line the pan with the cheesecloth. Dip the pound cake, slice by slice, in the rum and espresso soak, then use the slices to line the bottom and sides of the pan. (Dip the cake slices very quickly or they will become too soggy to handle, let any excess liquid drain from the slices before lining the pan.) Leave no gaps, patching where necessary with pieces of soaked pound cake.
In a large bowl, beat the egg yolks with the sugar until they turn pale yellow, about 4 minutes. Melt the chocolate in a double boiler over gently simmering water or in the microwave (2-3 minutes total, stirring every 30 seconds). Gradually pour the melted chocolate over the beaten egg yolks, mixing quickly with a rubber spatula until smoothly combined. In a medium bowl, beat the egg whites until the form stiff peaks. Stir a rounded tablespoon of the beaten whites into the chocolate mixture to loosen it, then gently fold in the remaining whites. Spoon the chocolate filling into the cake-lined pan. Cover the filling with more slices of soaked pound cake (you may have some cake left over). Fold the moistened cheesecloth over the top of the cake. Refrigerate the diplomatico for at least one day, and up to a week.
When you take the cake out of the fridge, unfold the cheesecloth and pull it away from the top of the cake. Invert the loaf pan onto a platter and shake it firmly to free the cake and peel off the cheesecloth. Slice and serve. You could garnish the slices with whipped cream and fresh fruit, but it also tastes just fine on its own.