Beat butter and sugar till well incorporated. Add in eggs one at a time while continuing to beat the batter lightly.
Fold in the flour a little at a time, till the batter is well mixed. Add in baking powder, condensed milk and vanilla essence.
Divide he batter into three separate bowls of equal measure. Add a different food colouring to each bowl.
Layer the cake batters one colour at a time on greased muffin cups. Bake in a 350 degree preheated oven for 20-25 mins or till done.