Instructions

1. Whisk three of the egg whites until stiff, then set aside.
2. Whisk the egg yolks and the fourth egg with the sugar until pale and voluminous, then whisk in the mascarpone, a little at a time, until smooth and well combined – you don't want lumps of cheese.
3. Gently fold the three whites into the mascarpone mixture with a large metal spoon, being careful to knock as little air out as possible.
4. Pour the coffee into a shallow dish. Dip each biscuit into the liquid (or brush the liquid onto each biscuit) until it is a pale coffee colour, then arrange to cover the base of a shallow glass dish.
5. Spoon a third of the mascarpone mixture on top, followed by a good sprinkle of cocoa, then repeat the layers, finishing with a layer of the cheese and cocoa.
6. Cover and refrigerate for six hours before serving – you may need to dust with a little more cocoa to make it look respectable.

Tips

• You don't want to dip the biscuit into the liquid for too long as it'll be too soggy in the dessert - 1-2 seconds on either side should be enough. Alternatively, you can brush the liquid on either side, so that at least two-thirds of the biscuit has absorbed the liquid.