How to Make an Easy Rainbow Cupcake Cake

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!

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.

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.

You can 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, 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).

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.

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. 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.

They still easily pull-apart and everybody gets plenty of frosting!

Love Rainbows? Check out these posts:

• Rainbow Fiesta Cake with Cactus Toppers
• 20+ Rainbow Cakes & Party Ideas
• Rainbow Chevron Painting Party Cake
• My Little Pony Rainbow Dash Cupcakes
• Elmo Rainbow Chevron Cake