Preheat the oven to 180 degrees C (gas mark 4). Line a bun tray with paper or foil cases. Sift together the flour, baking powder, bicarbonate of soda, cocoa and salt. Set aside.
In a large bowl, cream together the butter and sugar until light and fluffy. Add the eggs one at a time, beating well with each addition, then stir in the vanilla. Add the flour mixture alternately with the milk; beat well. Fill the paper cups 3/4's full.
Bake for 15 minutes in the preheated oven, or until a skewer inserted into the cake comes out clean. Ice with your favourite icing when cool.