Chocolate and caramel popcorn trifle

Method

1. First make the custard: heat the milk in a pan over a medium heat until steaming but not boiling. Take off the heat and add the 100g grated chocolate, stirring to help it melt and blend into the milk.
2. In a medium mixing bowl, use a balloon whisk to whisk the sugar and egg yolks, then sprinkle over the cornflour and mix until smooth. Slowly pour in the chocolate milk, whisking to incorporate, then transfer the mixture back to the pan. Cook over a medium heat, stirring all the time, until the custard
   thickens. Take off the heat, leave to cool a little, then stir in the mascarpone. Lay a piece of damp baking paper on the surface to stop a skin forming, then chill for 30 minutes.
3. Melt the 150g chocolate in a bowl set over a pan of barely simmering water (don’t let the bowl touch the water), stirring until smooth. Add the Rice Krispies/cornflakes, then fold them through the chocolate to fully coat. Spread the mixture on a baking tray lined with baking paper, then chill in the fridge for 30 minutes until set hard.
4. Put half the chocolate custard in a 20cm trifle dish. Add two thirds of the chocolate Krispies/ cornflakes, then spoon the remaining custard on top and smooth the surface. Cover and chill for 2 hours so the custard sets fully (see Make Ahead).
5. To make the popcorn praline, line a baking tray with foil and lightly grease. Put the sugar in a heavy-based frying pan over a high heat. Cook, shaking the pan occasionally, for 6-7 minutes until a dark caramel forms. Stir in the popcorn, remove from the heat and pour onto the tray. Cool, then break into shards. If you like, whizz half the praline in a processor to make coarse crumbs.
6. Just before serving, whip the cream until it holds its shape, then spoon the cream onto the trifle. Top with the popcorn and any crumbs, along with the rest of the chocolate Krispies/cornflakes, and serve.