Preheat an oven to 160 degrees/gas 3.

Line a 23cm springform tin top and sides with greaseproof paper and butter it well.

Melt the butter and chocolate together in a bowl over hot water on the hob. Then, in a small saucepan, simmer together the milk and the chestnuts until the chestnuts have softened a good bit – about 10 minutes.

Next, add the vanilla to the chestnut and milk mixture before blitzing the whole lot to a puree in a food processor. Keeping the mixture in the food processor, add the sugar, the egg yolks and the melted butter and chocolate, and blitz till smooth. Add the cognac and the coffee and blitz briefly to blend it in. Transfer the lot to a large bowl.

Finally, whisk the eggs whites till stiff and fold them into the chocolate mixture. Pour into the lined tin and bake for 20-25 minutes until it’s still wobbly. Cool completely before putting it in the fridge overnight. Remove from the fridge about an hour before you’re due to eat, and serve with redcurrants and cream.