Chocolate sponge with chocolate custard

Method

1. Preheat the oven to 180°C/fan160°C/gas 4. Grease and line a square 20cm cake or brownie tin.
2. Beat the butter with an electric hand mixer or in a stand mixer until soft, then add the sugars and beat for 5 minutes until light and fluffy.
3. Gradually add the eggs, beating well after each addition. Sift over the flour, baking powder and cocoa, then carefully fold through the mix along with the grated chocolate.
4. Add the vanilla extract and enough of the warm milk to create a smooth mixture with a dropping consistency. Pour into the tin and bake for 45-50 minutes or until a skewer inserted into the centre comes out clean.
5. Meanwhile make the custard. Heat the milk and cream together until almost boiling. Whisk the egg yolks in a bowl with the sugar, cocoa and cornflour, then pour the hot milk and cream over the top. Whisk well, then return to a clean pan.
6. Cook over a low-medium heat, stirring constantly, until it forms a custard that thickly coats the back of a wooden spoon. Set aside.
7. Turn out the sponge and cut into 8 equal squares. Serve warm with the chocolate custard poured over.