Bake your favorite cake recipe or mix in Butterfly pan following recipe instructions. Cool in pan on wire rack 10 minutes. Remove from pan and cool completely. Arrange cake on foil-wrapped cake board cut to fit.
Spatula ice cake sides and background areas smooth with thinned white buttercream; add tip 7 white ball bottom border. Tint remaining buttercream dark violet, light violet, black and yellow. Fill in butterfly details with tip 16 stars and violet and black icings; add yellow wing details and eyes and outline mouth. Insert small pieces of black shoestring licorice for antenna. Decorate antenna ends with yellow icing.