Share this post:

This Rainbow Cupcake Cake (also called a Pull-Apart Cake) is pretty and perfect for any rainbow-themed birthday party. It's easy to put together but looks so impressive and will feed a crowd! Use any flavor cake that you like to make this fun birthday cake!

Originally published January 2022, updated September 2023

Easy Rainbow Cupcake Cake

So let's get started with How to Make an Easy Rainbow Cupcake Cake!

This Pull-Apart Rainbow Cupcake cake was the perfect solution for a rainbow party where kids could help themselves to a cupcake versus having someone cut and serve cake.

And if your kiddo or client is asking for a rainbow cake, but wants to save money on the budget, this is also a great solution. I don't know about your cake business, but with mine, cupcakes are significantly less expensive than a decorated cake.

Jump to:

Easy Rainbow Cupcake Cake
Supplies You'll Need for a Cupcake Cake
How to Pipe a Rosette
Instructions: How to Assemble a Cupcake Cake
Pro Tips
Love Rainbows? Check out these posts:
Recipe

Supplies You'll Need for a Cupcake Cake

Here's what you'll need for this exact cake:

Cupcakes. You'll need approximately 4 dozen cupcakes for this rainbow pull-apart cake. Of course, the size can be adapted based on your needs. Bake the cupcakes in any flavor you like.

I included a vanilla cake recipe below but you can also use one of my favorite cake recipes, one of these popular recipes, or any recipe that you love. You could even go really basic and follow the directions on the back of a cake mix box. You'll need two batches of almost any recipe to yield 48 cupcakes.

You could get really fancy and use a white cake mix and make colored batter, but that was more work than I wanted to do for this cake.

I think this goes without saying, but you'll also need a cupcake pan and cupcake liners. I used my favorite standard brown liners (that I love), but you could go with white cupcake liners or coordinate them to your board.

You could also use mini cupcakes for a much smaller design.

Cake Board. For this cake, I used ~~a 20-inch by 16-inch cake board~~* a 20-inch x 30-inch foam board from Walmart, then covered it in white paper. You could also use a pre-covered cake drum if you like (and if you can find one large enough). (

*When I originally wrote this post, it was months after making the cake. I unintentionally put the wrong size board in the post. I'm inserting a (sloppy, thrown-together) mock-up of how I put the cupcake cake together using a (very old banged-up 20x30 board and empty cupcake liners), just to give you an idea of the layout with 48 standard-size cupcakes.

Buttercream Frosting. You're going to need all the ingredients to make a big batch of buttercream for this cake. I made this classic vanilla buttercream, but cream cheese frosting would also work. You probably know I recommend making buttercream in a Bosch Mixer... if you wonder why, check out this post. You will need approximately 19-20 cups. Here are the approximate amounts I used:

3 cups pink frosting
3 cups orange frosting
2.5 cups yellow frosting
2 cups green frosting
2 cups blue frosting
1.5 cups purple frosting
5 cups white frosting

Gel Colors. I only use Americolor Gel Colors to tint my frosting. And for this cupcake cake, I used tiny amounts of Electric Gel Colors: Pink, Orange, Lemon Yellow, Leaf Green, Sky Blue, and Regal Purple. Any gel food coloring brand would work!

Electric Mixer. I use my Bosch Mixer for making buttercream. You could use a hand mixer for mixing the gel colors into the frosting, but I usually do this by hand.

Bowls. You'll want a bowl and spoon for each color of frosting you want to make. I use paper bowls for easier cleanup, but small-to-medium mixing bowls would also work!

Piping Supplies. I love these 18-inch piping bags and a 1M tip. The Ateco #824 tip also gives a very similar look.

How to Pipe a Rosette

If you haven't ever piped a buttercream rose or rosette, there is a learning curve. If you need to practice first, do that on a clean plate or plastic cutting board. Then you can scrape the frosting off and use it again.

In fact, if you haven't ever done it, I recommend that you do several practice runs before working straight on a cupcake! It's much easier to scrape it back into your piping bag from a plate than it is off a cupcake!

When you're ready, here's a short video for you showing how to pipe rosettes on the tops of the cupcakes:

Instructions: How to Assemble a Cupcake Cake

Be sure you have a board big enough to accommodate your design. For a cupcake cake this size, I used a 20x30 inch foam board from Walmart. I wrapped it in floral paper to make it a bit prettier.

To make sure I can do the design I want, I check this by laying out empty cupcake liners into the shape I want so I know how many cupcakes I'll need.

I leave the liners in place, then replace them with real cupcakes one at a time, so I keep my design lined up. I do not frost my cupcakes before putting them on the board in the rainbow shape!

Also, I always cover my board with paper, unless it's a pre-covered cake drum. When you're ready to attach the cupcakes, pipe a small dot of buttercream onto the bottom of the cupcake and place it on the board. Apply a little pressure to be sure it's good and stuck.

After all the cupcakes are in place, I pipe overlapping rosettes to cover them and make a cohesive design. There will not necessarily be one rosette per cupcake. I like to have them all run together so it looks more like a whole cake instead of individual cupcakes.

Pro Tips

If the board you're using feels flimsy, use two boards, glued together with hot glue, then wrap them.
Lay out empty cupcake liners or the baked cupcakes on the board BEFORE frosting them. When you have them like you want them, pick them up one at a time and add a dot of frosting to the bottom to "glue" them in place. THEN frost them.
Because you're making multiple colors, use disposable piping bags for easy clean-up. Double bag them with the frosting tip in the outer bag, then the inner bag full of frosting to easily switch between colors.
Use a cookie scoop to put the cupcake batter in the liners so they're all even and the same size.
Add rainbow sprinkles to the batter to make them fun on the inside!
Make all the frosting a day or two ahead of time so that making the cupcake cake comes together quickly. The frosting can sit at room temp (covered tightly) for a couple of days so it'll still be easy to pipe.
In the recipe below, you can change the flavor of the cupcakes by changing the cake mix and pudding flavor. Use butter cake and vanilla pudding mix, chocolate cake and chocolate pudding mix, lemon cake with lemon pudding mix, strawberry cake with strawberry pudding mix, etc.

Love Rainbows? Check out these posts:

rainbow cupcake pullapart cake on white serving trays

Recipe