This cake came together while at my friend, Katie's house. She always has such fun things to make with the kids. It really was such a nice activity to do with them, especially since it was to celebrate their 3 year birthdays! We prepared this cake with a little help from our birthday girls, so we took an easier route than the original recipe called for in the below link. So feel free to make modifications/additions to the recipe you decide to make. By the way, what a nice treat for a birthday cake, since it was so fun and colorful! Here's our simplified version of rainbow cake! Enjoy.
Preheat oven and prepare cake pans as directed on cake mix box. We used 2 round cake pans for this, but I'm sure you can use square or whatever sizes you have. Prepare the boxed white cake mix as directed on box. Once batter is prepared and mixed well, pour it into 6 different bowls, equally, maybe about a cup into each. After batter is divided, add food coloring to each bowl. We used probably 10+ drops of food coloring in each bowl, and then mixed thoroughly to distribute the color. You can add as much as you’d like to your color preferences.
Once colors are mixed, begin to assemble the cake. See pictures for an idea of color assembly. We split the colors into the 2 pans and just poured each color directly into one another, creating the circular pattern in the cake. Continue until all of the colored batter is distributed.
Bake as directed on the box, or until cake tester comes clean. Let the cakes cool and then frost. We assembled our cakes to be a double-layer cake, but really it is up to you however you'd like to present the cakes. We used a canned frosting for both the filling between the two layers of cake and the top of the cake. Again, the best thing about this cake is that you can be flexible and modify this as you’d like. Enjoy!!
Original recipefound here: http://www.omnomicon.com/rainbowcake