Rainbow Cake, gluten-free

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Part of my busy schedule last month included my daughter’s birthday. She didn’t seem intent on any particular theme for her party, so I suggested rainbows. Seems like an easy cake to make, right? Right. I made it a little more interesting by adding some dimension to the rainbow.

For the base of the cake, I used three Betty Crocker Gluten Free Chocolate Cake Mixes. I mixed them all together using the directions on the boxes. Then, I poured the batter into two Pyrex 9×13 Baking Dishes and baked both at 350° F for about 45 minutes. Each layer of the cake was made of 1.5 cake mixes. I used Pillsbury Chocolate Fudge Frosting for the filling between the layers.

For the rainbow on the cake, I baked one 9-Inch Round Cake using Betty Crocker Gluten Free Yellow Cake Mix. I cut the cake in half, at a horizontal angle and then trimmed out the middle of the rainbow. I added a smaller wedge of the cake to put under the large side of the cake so the rainbow itself ended up being like a two-layer cake. Does that make sense? I know I should take pictures while I’m building and decorating cakes, but I forget. And when I do remember, I’ve got cake and frosting on my fingers.

For the frosting, I made a Buttercream Icing. Rather than using a dye to mix into the frosting, I sprayed the frosted cake with blue Spray Color. I thought the uneven coloring would look more like sky and clouds. Plus, it was faster and left fewer bowls to clean up. I used the same buttercream icing for the trim, clouds, and rainbow on the cake. Then, I sprayed the back of the rainbow cake with red coloring.

For the front of the rainbow I simply used different Colored Sugars that I carefully sprinkled on with my fingers. It’s best to do this right after you’ve frosted it, so that the frosting is still damp and sticky to keep the sugar in place. You can buy the sugars already colored, or make it yourself using granulated sugar mixed with some food coloring. I had some of each.

So there it is. Another cake decorating idea that you can do yourself, but still wow the kids.

Supplies I used:

More Rainbow Cake Ideas I found Online:

  • This six-layer Super Epic Rainbow Cake at Whisk Kid is a rainbow on the inside!
  • These rainbow Colorburst Cupcakes at Our Best Bites are just as colorful.
  • The Super-Duper Rainbow Cakes – in a Jar at off the (meat) hook would make beautiful table decorations, party favors, or gifts to give!
  • A variety of decorating ideas for rainbow-theme cakes can be found at Coolest Birthday



Wow, Heather. That is one cool cake. Do I remember other cool cakes in past years from you? I’ve been searching for ideas for my baby’s birthday/graduation party next week. Wonder how I should decorate her cupcakes?


Thanks Wendy. I do have fun with the kids’ birthday cakes. Last year, it was Hot Wheels and Princess and the Frog. But somehow I don’t think those will work for your daughter. I have done an ice cream cake that I frosted with chocolate icing, then surrounded it with cupcakes that were frosted with yellow icing. It looked like a sunflower. That was pretty fun for summer birthdays.


What a beautiful cake, Heather! Great job. I love the extra dimension to it. I miss (sort of) making kids birthday cakes. I’m sure your daughter liked hers.


Thanks Linda. My daughter did like the cake, but I think she would’ve been happier if I let her do more of it. 🙂 I think we’ll bake some cakes this summer just to let the kids decorate them.


I’m so in awe of your artistic touch! It’s quite impressive. Loved last years’, too.

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