Step 1

Put the chestnuts in the food processor with the sugar, then process until fairly smooth. Put the butter and chocolate in a pan with the milk, then gently heat, stirring, until they have melted to a smooth sauce. Stir in the vanilla and cognac. Add to the chestnut mix in the food processor, then whizz again until fairly smooth.

Step 2

Line a lightly buttered small loaf tin with cling film, then pour in the chestnut truffle mix. Smooth the top, then cover the tin with cling film. Chill for 24 hrs.

Step 3

To serve, turn the truffle cake out onto a flat plate or board. Peel off the cling film. Gently melt the chocolate, butter and cream for the topping, then spread over the top and sides of the cake. Return to the fridge to set. Will keep in the fridge for another 6 days. Decorate with a dusting of icing sugar. Serve cut into thin slices with a little single cream poured around (cold vanilla custard is also very good).