Rainbow cakes make everyone happy. It's just a fact of life. This rainbow cake will make you extra happy because it uses boxed cake mix for the easiest (but still amazingly delicious!) way to make such a fun cake.
Keyword: cakes, semi-homemade cakes
3boxeswhite cake mix, whatever brand you prefer
1can white frosting*
eggs, vegetable oil, water (as called for on your cake mix)
1packagegel food coloring
Preheat oven to 325 (or whatever package on cake mix calls for), and spray six 8" round cake pans with non-stick cooking spray line bottoms with parchment paper. Set aside.
In a very large bowl, make a triple batch of batter according to the package directions.
Measure batter evenly into each of 7 bowls, starting with a cup of your cake batter in each bowl and slowly adding the same amount to each. Add gel food coloring with a toothpick to each bowl until you reach your desired color. (The 7th bowl is there only in case you mess up with a color)
Pour batter into each cake pan and bake for approximately 10 minutes or until a toothpick inserted in the center comes out clean. Remove cakes from oven, let cool for 5-10 minutes, then quickly flip to a cooling rack to dry completely.
When cake is completely cool, place bottom layer (red) down on a cake plate or other flat surface. Add thin layer (about ¼") of icing on the inside of each layer using a pastry bag to make sure the layers stack nicely. Add next layer and frost again. Continue frosting each layer until you get to the top. Stick the cake in the refrigerator for 10 minutes then ice the outside of the cake with a light crumb coating. Stop at this point (like I've done) and enjoy it or put the cake in the refrigerator for another 10-15 minutes and frost the rest of the cake.
*For both the frosting, be sure to buy WHITE cake mix and frosting, not vanilla or yellow or cream cheese. This'll ensure you're able to make your cake into the most vibrant color possible and so that your white icing pops.Storing: Store cake at room temperature covered to maintain freshness. The cake will be delicious 2-3 days later.