550g/19oz self-raising flour
550g/19oz caster sugar
550g/19oz very soft butter
4 tsp baking powder
2 tsp vanilla extract
4 tbsp milk
4 tbsp dark cocoa powder and a little boiling water
For the icing
500g/1lb cream cheese at room temperature
200g/7oz icing sugar
Heat the oven to 200C/400F/Gas6. Mix the first seven ingredients together in a food processor; you may have to do this in two batches. Put the cocoa powder into a bowl and add enough boiling water to make a loose paste. Stir this into the cake mix.
Butter and flour three 20cm spring-form cake tins and divide the cake batter evenly between all three. Put the tins on the middle shelf, or bake one after the other if your oven is too small to hold all three. Bake for 20 minutes, then remove and allow to cool to room temperature.
To make the icing, put the cream cheese in a bowl and sift the icing sugar over the top, then beat well to combine. Divide the icing into three, leaving just a little to ice the sides of the cake, and spread generously over one side of each cake. Pile on top of each other and ice the sides.
Grate a little good-quality dark chocolate over the top and place in the fridge to let the icing set.