Ingredients:
Flour                   100 g
Margarine               75 g
Egg                     1 no.
Vanilla essence         1/2 tsp
Baking powder           1 level tsp.
Sugar                   75 g
Cocoa                   1 tsp
Milk to mix



Method:
1.  Cream the fat and sugar together in a mixing bowl until light and fluffy.
2.  Add the egg gradually and continue creaming.
3.  Add the vanilla essence.
4.  Sift the flour and the baking powder together.
5.  Add the flour to the creamed mixture, folding in with a metal spoon.
6.  Add sufficient milk to form a dropping consistency.
7.  Put 1/3 of the mixture in another mixing bowl.
8.  Add the sifted cocoa to this and mix well.
9.  Pour half the plain mixture, then the chocolate mixture and then the 
    remaining plain mixture into a greased sandwich tin or a loaf tin.
10. Using a skewer, make circular movements in the cake mixture to give the 
    marbling effect.
11. Bake in a hot oven, 200oC (400oF) or Reg. 6, until 
    goldenbrown (about 30-40mins).
12. Cool on a wire rack.
13. Cut into pieces and serve on a plate.