1 For the cake: heat the oven to 170°C (150° fan) 325°F gas 3. Grease a buttterfly shape cake tin, 28 cm x 21 cm x 5 cm |11" x 8½" x 2" deep.
2 Beat the butter and sugar in a mixing bowl until light and fluffy.
3 Gradually beat in the eggs, one at a time until smooth.
4 Sift in the flour and stir gently until combined. Stir in the vanilla.
5 Spoon into the tin and bake for 60-75 minutes until risen and golden and firm to the touch. Cool in the tin for 10 minutes, then place on a wire rack to cool.
6 For the decoration: mix the royal icing sugar with a little water, adding a little at a time, until it is thick and smooth and of a piping consistency. Divide the icing in half. Divide 1 half into batches, adding a different colour to each. This will leave a larger amount of white icing.
7 Spoon the icings into separate small plastic bags and cut off the merest tip of each bag, to allow the icing to be piped.
8 Pipe white icing down the centre of the cake, to form the 'body' as in the photo. Pipe the top half of the wings with white icing.
9 Pipe pink icing for the lower wings and use the remaining pink icing to pipe on top of the white iced wings. Pipe white icing on top of the pink icing as in the photo.
10 Pipe an outline of the butterfly using the yellow icing. Pipe the blue icing as in the photo.
11 Decorate the butterfly with coloured chocolate beans, sugar sprinkles and the sparkling sugars as in the photo. Leave to set.