For me (and Italians would kill me for saying this), tiramisù is the coolest trifle in the world. The Venetians don’t really have many desserts, but this is a classic. It’s usually dead simple and all about the sponge, the coffee and the cream, but I think chocolate and coffee are such good friends that you’ve got to get a bit of chocolate in there. I’ve also used egg whites, which isn’t traditional, but they make it lovely and light and spread the mascarpone about so it’s not so rich.
Put a glass bowl over a pan of gently simmering water, making sure the water doesn’t touch the base of the bowl. Put 200g of the chocolate into the bowl, keeping the remaining 50g in one piece. Add the diced butter and a pinch of salt, and leave for 5 minutes or so until melted and combined. Help it along by giving it a stir every now and then.
Meanwhile, line a large, deep bowl or round earthenware dish (about 30cm in diameter and 12cm deep) with the sponge fingers, then carefully pour over the hot sweetened coffee. Add a couple of swigs of vin santo to your melted chocolate, stir it through, then drizzle all over the sponge fingers. Use a spatula to carefully smooth it out to the edges so you’ve got a nice even layer. Put it to one side to cool.
Separate your eggs, putting the whites into one bowl and the yolks into another. Add the sugar to the yolks with another swig of vin santo (if you’re feeling naughty!), and whisk with an electric whisk on the highest setting for about 5 minutes, or by hand, until all the sugar has dissolved and the yolks are pale and fluffy. Mix in the mascarpone and the zest of 1 orange.
Clean and dry your whisk, and whisk the whites with a pinch of salt until they form stiff peaks – they should be a similar consistency to the yolk and mascarpone mixture, and should hold their shape when you lift the beaters from the bowl.
Using a large metal spoon, add a spoonful of your whites to the yolk mixture and gently fold them in, then fold through the rest of the whites. Spoon and smooth this creamy mixture on top of your chocolate layer.
Scatter the finely bashed-up coffee beans over the top. Using a sharp knife or a speed peeler, carefully shave over your remaining chocolate. Finely grate over the zest from half your remaining orange. Pop the tiramisù into the fridge for 2 hours to set.