I had a difficult time thinking of a name for this cake. I really wanted to create a cake that mimicked the arch of a rainbow, and wanted the name to reflect it. Calling it just a “rainbow cake” didn’t seem sufficient. “Rainbow layer cake” also brought a different looking cake to mind. I finally came up with the “over the rainbow” name, and thought it fit. This cake took me an inexcusably long time to make. My motivation has needed a kick in the pants the past few weeks.
I used this cake pan to bake the white cake mounds. It produced perfect half-spheres of cake about 3.5″ in diameter. The finished cake ended up being about 8 inches in diameter. This recipe yields two cakes, which would be enough to feed a large party of guests.
This recipe makes enough for two rainbow cakes. If you want to make the cake from scratch, just double a recipe for a white layer cake.
- Prepare batter from one box of cake mix. Pour cake ¾ of the way full into two ball-shaped cake cups. Divide remaining batter into 3 bowls, staggering the amounts of batter in each bowl. Tint the bowl with the least amount of batter with violet. Tint the bowl with slightly more batter with blue, and tint the bowl with the most amount of batter green. Coat three 8-inch cake pans with non-stick spray.
- Pour each shade of cake batter into a separate cake pan (it’s okay if the cake batter doesn’t completely cover the bottom of the pan). Bake white cake mounds and the three cake pans in the oven at 350ºF for about 18-20 minutes, until cake is set in the middle. Cool for 10 minutes on a wire rack, then remove cake from pans and cool completely.
- Prepare batter from second box of cake mix. Divide batter into three bowls, once again staggering the amounts in each bowl. Tint the bowl with the least amount of batter yellow; the bowl with slightly more batter orange; and the bowl with the most batter red. Repeat baking instructions, increasing the baking time as needed. Cool cake for 10 minutes on a wire rack, then remove from pans and cool completely.
- Level the mounds of white cake so they sit flat against a cardboard round. Crumble the purple cake in a bowl and mix with a little bit of frosting (cake crumbs should stick together when pressed into a ball). The consistency should be a bit dryer than that of cake pops. Coat the white cake mounds with a thin layer of frosting. Cover cake mound with a layer of purple cake, patting the crumbs together in an evenly across the entire surface. Chill for an hour. Repeat process with remaining cake colors, coating each layer thinly with frosting before adding a new color on.
- Frost the red (and final) layer. Chill before serving.