Method

1. Separate the egg yolks and the whites into 2 bowls. Vigorously whisk the yolks, slowly adding 2 ½ tbsp of caster sugar until pale and frothy. Now vigorously whisk the whites, slowly adding the rest of the caster sugar, until standing in stiff peaks.
2. Add the mascarpone and vanilla essence to the egg yolks and fold in gently. Now pour in the egg whites and again fold them in gently.
3. Wipe the empty bowl clean, add the double cream and whisk until just thickened. Fold this gently into the egg mixture.
4. Now use the beans to make a strong black coffee in a cafetiere or simply pour the boiling water over the coffee in a heatproof bowl and strain it after a few minutes. Pour the coffee into a mixing bowl and add the marsala and brandy. Stir and allow to cool.
5. In a large deep dish about 30x20cm and about 10cm deep, spread a 5cm thick layer of mascarpone mixture over the base. Take the sponge fingers one by one and quickly dip them into the cooled coffee mixture for only 1 second per finger and place over the mascarpone mixture in rows. Continue until you have a layer of biscuits, then pour over another 2.5cm thick layer of mascarpone mix. Repeat the layers, finishing with the mascarpone mix. Finely grate the dark chocolate over the top and chill in the fridge for at least 3-4 hours before serving.