Beat the 3 egg yolks with the sugar in a mixing bowl until pale and thick. Add the mascarpone gradually and 1 teaspoon espresso coffee, and stir to combine.
Whisk the egg whites until stiff. Stir 1/3 of the egg whites into the mascarpone and egg yolk mixture, then mix thoroughly the remainder. Add 1 teaspoon brandy, if desired.
Combine the coffee espresso and milk with nescafe in a medium bowl. Dip a third of biscuits, one at a time, into the mixture to moisten.
Arrange the soaked biscuits, one by one, in a deep 8-in (square, round or oval) oven dish. Spread 3 tbsp of the mascarpone cream and sprinkles chocolates pieces. Repeat layers, dipping more biscuits in the coffee mixture, covering with mascarpone cream and chocolate pieces.
Cover with a final layer of soaked biscuits. Pour a little of the remaining coffee mixture over the biscuits and top with the remaining cream and grated chocolate.
Cover and refrigerate for at least 6 hours. Overnight is the best. To serve, dust generously with cocoa powder, if you want.
