Directions

1. Beat the egg yolks, sugar, the vanilla, a grating of nutmeg and 50ml of the marsala using an electric whisk in a heatproof bowl over a pan of barely simmering water for 10 mins, until pale and light. Put in the fridge to cool.
2. In a separate bowl, beat the mascarpone and cream together with an electric whisk until the mixture holds soft peaks. Gently fold the egg yolk and cream mixtures together with a spatula, being careful not to over-stir. Put the bowl back in the fridge to chill.
3. Scatter a little sugar over the base of a deep 20 x 20cm serving dish. Pour the coffee and the remaining 100ml marsala into a bowl. One by one, dip 12 biscuits in the coffee mixture on each side for a couple of seconds (don't leave them too long or they'll go soggy), then lay flat in the dish to cover the base. Spread over half the cream mixture. Dip the remaining biscuits in the coffee and arrange on top of the cream, then finish with a final layer of the cream. Cover the dish and chill for at least 3 hrs.Can be made up to two days in advance.
4. To make the crunchy topping, put the sugar and a splash of water in a saucepan, and stir to combine. Simmer over a medium heat until you have an amber-coloured caramel. Pour the caramel onto a parchment-lined baking tray and tilt to spread. While it's still hot, dust with the coffee and cocoa powder, then leave to set until hard. Break into small pieces, then blitz in a processor to a rough crumb. Sprinkle over the tiramisu and dust with a little cocoa powder to serve.