Put margarine, sugar, eggs, flour and milk in a bowl together and mix with either a mixer or electric whisk

Divide into 2 bowls. In one bowl, add cocoa powder and mix again till chocolate brown.

Put one tbsp of each mix into each cupcake case. You can either leave them as they are or mix till marbled.

Put in the oven, 180'C for 15 - 20 minutes or until well risen. Leave to cool for 20 - 25 mins.