1. Beat the egg whites until stiff peaks form.

2. Grate the dark chocolate.

3. In a bowl, combine the egg yolks and sugar, and beat them together with a wooden spoon until they are white and fluffy.

4. Gently fold in the mascarpone and then the beaten egg whites.

5. Cover the bottom of a high-sided rectangular serving dish with a layer of ladyfingers and brush them carefully with the espresso coffee.

6. Cover them with a layer of mascarpone cream and sprinkle with some grated chocolate.

7. Continue to alternate layers of ladyfingers, coffee, and mascarpone cream until all the ingredients are used up.

8. The top layer should be mascarpone sprinkled with cocoa.

9. Place the dessert in the refrigerator for about 3 hours.