German Cake Squares

For the cake: heat the oven to 180°C (160° fan) 350°F gas 4. Grease a 23cm x 33cm|9" x 13" baking tin.

Beat the butter and sugar in a mixing bowl until light and creamy. Add the eggs, one at a time, beating well, then add the vanilla.

Sift in the flour and baking powder and mix until blended. Stir in 1-2 tablespoons milk so that the mixture is a soft dropping consistency. Spread half the mixture in the baking tin.

Sift the cocoa into the remaining mixture and stir until combined. Stir in the remaining milk so that the mixture is a soft dropping consistency. Spread on top of the plain mixture, swirling the mixtures together a little.

Arrange the cherries evenly over the top of the mixture. Bake for about 35 minutes, until cooked through. Cool completely in the tin.

For the filling: mix the custard powder with a little of the milk to form a paste. Heat the remaining milk in a pan and bring to a boil. Whisk in the custard paste and boil for 2 minutes, whisking constantly until thickened. Cover and leave to cool to room temperature.

Beat the butter and icing sugar until soft and creamy. Whisk in the custard mixture, a spoonful at a time until light and fluffy. Spread over the cake and chill until the custard has set firmly.

For the topping: melt the chocolate and butter in a heatproof bowl over a pan of simmering (not boiling) water. Remove from the heat and stir in the icing sugar.