1. Preheat the oven to 180°C (160°C Fan, Gas Mark 4). Grease and line a 7cm (2 ¾ inch) deep, 12cm (5 inch) round cake tin. Beat the margarine and sugar together until pale and creamy then beat in the eggs.
2. Sieve the flour, Cocoa and Baking Powder on top. Using a large metal spoon, fold the dry ingredients into the creamy mixture until well blended.
3. Spoon into the prepared tin, smooth the top and bake in the oven for 45 minutes, until risen to the top of the tin and a skewer inserted into the centre of the cake comes out clean. Cool for 5 minutes then turn on to a wire rack to cool completely.
4. To decorate, put the butter and Madagascan Vanilla Extract in a bowl and gradually sieve and mix the icing sugar into the butter to make a smooth, creamy icing. Add a few drops of Bright Red Gel Food Colour to make a pastel pink shade.
5. Carefully slice the cake into 3 equal rounds. Spread 2 of the rounds with two thirds of the icing and then sandwich the 3 cakes together. Spread the remaining icing on top and decorate with Wafer Butterflies to serve.