Forget chocolate brownies or ‘death by chocolate’. For the ultimate chocolate cake, this one beats all comers.

120g raisins
4 tbsp whisky
250g McVite’s Rich Tea biscuits
350g dark chocolate, broken into small pieces
120g butter
120g sugar
1 egg, beaten
Melted white chocolate to decorate (optional)

Put the raisins into a small bowl, pour on the whisky and leave to soak for an hour. Line a 20-cm square cake tin or baking dish with non-stick baking paper. Break the biscuits into small pieces, but don’t crust them. Melt 150g of the chocolate either in a microwave or over hot water.

Cream together the butter and sugar until light and fluffy, beat in the egg, then add the melted chocolate. Stir in the broken biscuits, mixing well so they are completely coated, then add the rasins. Put the mixture into the tin and level it off. Cover the tin with clingfilm and chill in the fridge for several hours.

Turn the cake out on to a wire rack standing over a large plate and peel off the baking paper. Melt the remaining chocolate, let it cool, then using a palate knife, swirl the chocolate over the cake and chill until set. If using white chocolate to decorate, randomly squiggle it over the cake, then chill again. It is very rich, so cut into small squares to serve.