Separate the eggs, then whisk the whites until they form stiff peaks and set aside. Add the sugar to the egg yolks, then whisk until light and frothy, and add the mascarpone, little by little, whisking constantly, until completely smooth.

Gently fold the whipped egg whites into the egg yolk and mascarpone mixture.

In a shallow dish, add the Marsala wine to the espresso and stir. Dip the sponge fingers into the liquid just until they start to darken, but don’t leave them to get soaked through.

To assemble, place a layer of sponge fingers into the bottom of a serving dish, then spoon over about a third of the mascarpone mixture. Sift over a layer of cocoa. Repeat with another layer of sponge fingers and mascarpone. Finish with a dusting of cocoa.

Cover and refrigerate for a few hours. Before serving, garnish with shards of dark chocolate.