Mix egg yolks and sugar well. Add Mascarpone, a little at a time, to egg yolk mixture and mix until smooth. Set aside. In a separate bowl, beat whipping cream until stiff peaks form. Set aside. In another bowl, beat the egg whites until stiff peaks form. Set aside. Fold the whipped cream into the egg yolk mixture, then fold in the egg whites to mix. Spread about 1/3 of the cream mixture in the bottom of a 4-6 quart glass baking dish or serving bowl.
Place espresso coffee in a large mixing bowl. Quickly dip a lady finger into the espresso, then lay it in the baking dish, on top of the cream mixture. Top with grated chocolate. Continue in this manner, laying the lady fingers side by side to cover the bottom of the dish. Place another 1/3 of the cream mixture on top of the soaked biscuits. Cover this with another layer of espresso soaked lady fingers. Top with the remaining cream mixture and grated chocolate. Dust the final layer of cream mixture with grated chocolate and cocoa powder. Chill 2 hours to set.