Rainbow Cake

I usually don’t love to bring up politics where they don’t belong, but this weekend is fitting. I had planned on making this rainbow cake for weeks and finally got around to creating it yesterday. Just as I finished up the cake last night, New York voted to allow gay marriage. Serendipitous timing! I send love and congratulations to all of the LGBTs in New York — we’ve only got 40-something more states to go! I also mentioned to a friend of mine that this newly passed law could single-handedly save our economy — gays planning weddings! :)

Alright, on to the instructions for this cake. I’ll likely never bring up politics again on my baking blog, so rest easy to those of you who don’t agree with my views.

This cake was not difficult to make, but it was very time consuming. I think it worked on it for about 5 hours, so it was a labor of love! I think it would make a great cake for a kids birthday party. I was OBSESSED with rainbows when I was a little girl and my parents would always buy a rainbow cake from our local bakery. My cakes had four layers (pink, yellow, green, and purple) and included raspberry filling between the layers. I remember the anticipation and excitement of cutting into the cake and seeing all of the colors. So much fun!

Rainbow Layer Cake
Recipe adapted from: The Tasty Kitchen
Print Recipe

For the cake:
2 boxes white cake mix (plus ingredients like eggs and oil, as called for on the box mix)
Red, orange, yellow, green, blue, and purple food coloring
*note: I used whole milk instead of water as called for by the directions, I think it leads to a denser and more tasty cake

For the frosting:
1 stick unsalted butter, softened
1 stick salted butter, softed
1 cup shortening
1 Tablespoon clear vanilla (if you want WHITE frosting)
2 lbs powdered sugar
4-6 Tablespoons milk
* note: You may need to make a double batch of this frosting; the rainbow cake is quite tall and uses a lot of frosting to cover it, so be sure that you have enough of the frosting ingredients on hand in case you need to make another batch!

1. Preheat oven to 350F and make 1 box cake mix according to box directions. Separate the batter into 3 bowls with roughly 1 cup of cake batter per bowl. Add food coloring (purple, blue, green) to each.
2. Spray three 8″ round cake pans with nonstick spray. Bake cakes for about 17-20 minutes — because of the small amount of batter, the cake does not take long to bake. Be sure to check on the cakes periodically to make sure they are not over-baking. Remove cakes from oven and cool on wire racks.
3. Repeat this process with another box cake mix, this time adding red, orange, and yellow food coloring. You will end up with six cakes when you are finished baking.
4. For the frosting, cream the butters and shortening together. Add the vanilla. Slowly add the powdered sugar until incorporated. Add 4-6 Tablespoons of milk as needed to thin the frosting.

Cake assembly:
1. Level each cake with a large bread knife. This is important because the cake layers will not sit evenly if they are not leveled… and your cake won’t be as pretty as it could be! Don’t worry about being perfect, just try to get rid of the little dome that forms on top of baked cakes.
2. Start with the PURPLE layer first. Once leveled, place the purple layer on your cake stand or plate (I usually “glue” the first layer down by placing a small amount of frosting in the middle of the cake stand, and then placing the cake on top). Add enough frosting to cover the purple cake.
3. Add the BLUE layer of the cake on top of the purple layer. Add enough frosting to cover the top of the blue cake.
4. Add the GREEN layer of the cake on top of the blue layer. Add enough frosting to cover the top of the green cake. At this point, you will have a three layer cake. Spread enough frosting around the outside of the cake to coat the entire cake — this will be your crumb coat. Don’t worry if it’s messy and don’t try to be clean and perfect here — just make sure that all of the cake is covered in frosting.
5. Freeze your cake for 1 hour or refrigerate for 2 hours.
6. Remove cake from the freezer or refrigerator and place the YELLOW layer on top of the green layer. Add enough frosting to cover the top of the yellow cake.
7. Add the ORANGE layer of the cake on top of the yellow layer. Add enough frosting to cover the top of the orange cake.
8. Add the RED layer of the cake on top of the orange layer. Add enough frosting to cover the top of the cake. At this point, you will have a six layer cake. Spread enough frosting around the outside of the yellow, orange, and red layers. Again, this should not be perfect. Just slap some frosting onto the cake and get it covered!
9. Freeze or refrigerate the cake one more time before beginning the final coat of frosting. Cooling the cake down helps to keep it stable and prevents it from wobbling. It is also MUCH easier to frost frozen cakes.
10. Once cooled, remove the cake from the freezer or refrigerator and begin the final stage of frosting. This is where you will be able to make the cake look more smooth and pretty. Add more frosting to the cake to thoroughly coat. Use an off-set spatula for this and dip it into hot water to help smooth the frosting over the cake. If you’d like, add some frosting to a pastry bag and pipe a few polka dots or decorations on top of the cake.


8 thoughts on “Rainbow Cake”

Leave a Reply

Your email address will not be published. Required fields are marked *