Pre-heat the oven to 180°C/160°C Fan/Gas Mark 4. Place the Muffin Cases into a cupcake tin.
Cream together the butter and sugar until light and fluffy. Gradually beat in the eggs, if the mixture starts to curdle, add a little flour. Fold in the remaining flour and the Cocoa Powder with a metal spoon.
Place spoonfuls of the mixture into the Muffin Cases and bake for 15-20 minutes until well risen and firm to the touch. Remove from the oven and leave to cool on a cooling rack.
Take a sharp knife and cut a circle out of the top of each cake at an angle about 1cm (½ inch) from the edge.
Dollop a spoonful of icings onto each cupcake and place the sponge circles on top of the icing. Dust the top of each cake lightly with icing sugar.