• Using a large serrated knife, cut the dome off the top of the cake and flip over.
• Slice the cake in half to form two half circles for your rainbows. You can carve out a semicircle to form the bottom of the rainbow, or you can just leave it and frost it white without the colorful candies, to create the illusion of a rainbow shape, whichever you prefer.
• Using an offset spatula, crumb coat your cakes with white frosting.
• Chill in the fridge for at least one hour or overnight.
• Frost your crumb-coated cakes with a thick coat of white frosting. Use an offset spatula to smooth it and make sure everything is covered.
• Your rainbow pattern will be determined by the size of your cake and candies, as well as desired effect. To determine your color pattern, use different colored candies to form a straight line starting from the highest point of the arch down to the bottom of the cake. If you didn’t carve out a semicircle you can opt to leave a portion of the cake without candies as per note above. This is the foundation for the colors of your rainbow. You can choose to represent all the colors of the rainbow each in a single row (red, orange, yellow, green, blue, purple etc...) or two rows each of fewer colors.
• Fill in the rows of candy to form a rainbow pattern.

DRESS IT UP

• Create a double decker rainbow cake by stacking the two half circles on top of each other with a thick layer of frosting in between, crumb coat, and proceed as directed above.