Rainbow Frosting

To get your frosting to go on in a swirl of color, dye regular buttercream frosting into separate colors. Place spoonfuls of each color side by side in a pastry bag working your way to the top of the bag. Starting at 12 o'clock on the outer edge of each cupcake and using constant pressure on the pastry bag, pipe frosting clockwise for three rotations, working your way toward the center ending in a little peak.