Directions

1. First make the coffee soaking liquid for the sponge fingers. Stir the coffee and sugar together, then pour into a shallow heatproof dish. Stir in the Marsala and leave to cool.
2. Meanwhile, prepare the filling. Put the sugar and cornflour into a medium saucepan, preferably non-stick. Stir in 1 tbsp of the measured milk to make a thin, smooth paste. Separate the egg, putting the white into a medium bowl and setting it aside, and dropping the yolk into the saucepan. Beat the yolk into the cornflour paste, then stir in the rest of the milk. Scrape the seeds from the vanilla pod into the pan, then drop in the pod. Cook over a medium-low heat for about 8-10 mins without letting the mixture boil, stirring all the time, until the mixture thickly coats the back of a wooden spoon. Remove from the heat, then stir in the creme fraiche and the 1 tbsp of Marsala. Transfer the mixture to a bowl, cover the surface with cling film and leave until cold.
3. To assemble, line a 23 x 13 x 6cm deep loaf tin with cling film (see step 1), leaving an overlap at the top. Beat together the mascarpone and soft cheese, then stir into the rest of the cold filling. Whisk the egg white to stiff peaks and gently fold into the filling using a large metal spoon.
4. Dip one of the sponge fingers in the coffee mixture, rolling it around briefly, for a few secs only, to coat and soak in, then lift it out before it has a chance to get too soggy (see step 2). If left in the coffee, it will disintegrate. Lay it lengthways in the bottom of the tin. Do the same with 5 more of the sponge fingers, trimming to fit if necessary, so that they cover the bottom of the tin. Spoon over half of the filling, spreading it to cover the biscuits (see step 3), then repeat the biscuit dipping with 6 more of them. Spoon and spread over the rest of the filling, then dip and lay the rest of the sponge fingers over the top (see step 4). Bring the cling film overhang over to cover. Chill overnight.
5. To serve, turn out onto a serving plate and carefully peel off the cling film. Dust the top with cocoa and scatter with raspberries, if using. Slice and serve the same day.