Take 300 gms butter and add 600 gms icing sugar. Whisk well and add 2-3 tbsp milk and food colour. whisk well and fill the frosting in a piping bag. Cut the top mount of the cake and slice it into two layers. Place the upper layer at the bottom and pipe out the frosting. Place the lower layer at the top and crumb coat the cake. Spread the frosting evenly and make rosettes. Decorate the cake with sprinklers.