Sift the flour and baking powder into a bowl. Add the butter, eggs, food colouring and sugar. Beat together until well mixed. If the mixture is a little thick, mix in a little milk.
Evenly divide the mixture between the cake cases. Bake for 20 minutes in a preheated oven (180c/Gas Mark 4) until just firm.
Allow to cool slightly before putting them out on a wire rack to cool completely.