Chocolate and vanilla traybake

Homemade chocolate and vanilla traybake, topped with milk and plain chocolate. Mmmmmmm!

In case anyone's interested,
Ingredients:
8 oz soft margarine
8 oz caster sugar
10 oz plain flour
3 teaspoons baking powder
4 eggs
2 tablespoons milk
½ teaspoon vanilla essence
1½ tablespoons cocoa powder
2 tablespoons hot water
2 oz chocolate chips
For the icing:
2 oz plain chocolate
2 oz milk chocolate

Method:
Pre-heat the oven to Gas Mark 4.
Grease and line a 12 x 9 inch tin with greased greaseproof paper.
Mix the margarine, sugar, flour, baking powder, eggs, milk and vanilla essence.
Spoon half the mixture into the prepared tin, dotting the spoonfuls apart.
Blend the cocoa and hot water. Cool slightly, add it and the chocolate chips to the remaining cake mixture. Spoon this chocolate mixture in between the plain cake mixture to fill the gaps.
Bake for 40 minutes or until the cake has shrunk slightly from the sides of the tin and springs back when pressed in the centre with your fingertips. Leave to cool in the tin.
Melt the plain and milk chocolate separately. Spoon into two separate small plastic bags, snip off the corner of the bags and drizzle the chocolate all over the top of the cake. Leave to set for about 30 minutes before cutting into squares.