1. Stack cake layers, spreading vanilla icing between each layer. Completely cover cake with more icing. Smooth tops and sides with a palette knife or spatula.
2. Squeeze gel icing on top of cake to make a colour wheel (each wedge should be a different colour). Squeeze icing down the top edge of cake to make "paint drippings."
A version of this article appeared in the November 2013 issue of Today's Parent.
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