Orange Buttercream Icing - Replace milk with orange juice and add the fine zest of one orange. Orange food colouring can be added as needed to colour the icing.
Preheat the oven to 180˚C. Grease 2 x 22cm deep round cake tin and line the base with baking paper.
Cream the butter, sugar and vanilla essence until light and fluffy. Add the eggs one at a time, beating well after each addition.
Sift the cocoa, flour and baking powder together and add to the creamed mixture alternately with the milk. Divide mixture between the prepared tins.
Bake for 30-35 minutes or until the cake springs back when lightly pressed and a skewer inserted into the centre comes out clean. Leave in the tin for 10 minutes before turning out onto a wire rack to cool.
When cold, sandwich cakes together with Chocolate Buttercream Icing and top with Orange Buttercream Icing.