Make cupcakes. Prepare batter following recipe directions. Divide batter into thirds. Use icing colors to tint one third batter each light rose, light blue and yellow. Use blue batter in disposable decorating bags to pipe first layer into baking cup. Repeat with a layer of yellow batter, then a layer of rose, until cup is 2/3 full with batter. Bake and cool cupcakes.
Prepare buttercream icing following recipe directions. Use spatula and icing to ice cupcakes smooth.