Magical and show stopping, this rainbow cake features layers of tender-crumb cake in various colors accented by vibrant white buttercream frosting. Completely fun and undeniably delicious, this will delight people of all ages.

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A rainbow birthday cake with a slice out of it.

Rainbow Cake Recipe

I cannot get over how pretty this Rainbow Cake is! The vibrant rainbow layers sandwiched by a white buttercream that is silky smooth –mmmmhmmm, give me more of that! This is the perfect Rainbow Birthday Cake, St. Patrick’s Day celebration cake or baby shower cake with rainbow for a sweet rainbow baby.

But looks aren’t everything. Which is why it’s a really good thing that this cake is really, really good. It is the perfect vanilla-y, buttery flavor with a moist/tender/fluffy texture that will make you feel like you picked it up from your nearest bakery. All I’m saying is you’re going to be glad it is 6 layers tall because you’re going to want every single bite.

What Ingredients Are In Rainbow Cake?

Cake

Salted butter, melted – I always use salted butter! You are welcome to use unsalted butter, if you’d prefer. Just be sure to add an extra pinch of salt to the batter.
Canola oil– we use both butter and oil in this recipe to give the cake a super spongey and moist crumb.
Granulated sugar
Eggs, room temperature – Cold eggs? No problem. Quickly bring eggs to room temperature by placing them in a bowl of warm (almost tepid) water for a few minutes.
Vanilla extract
Butter flavor – Try my high-quality, super-strength Butter Flavoring! This flavor is what will give your cake that bakery taste.
Cake flour – The cake flour will help your cake maintain a fluffy softness and tender crumb.
All-purpose flour– this is what will give our cake more structure so it won’t fall while baking.
Baking soda
Baking powder
Salt
Buttermilk, room temperature – Buttermilk is KEY to the light, fluffy, and tender texture of this cake!
Food coloring – I find that gel works best, but regular food coloring will also work if needed.

Vanilla Buttercream

Salted butter, softened – Again, unsalted will work too.
Powdered sugar
Clear vanilla – You can sub regular vanilla, your frosting just won’t be bright white.
Rainbow colored sprinkles

A birthday cake frosted with rainbow sprinkles.

How to Make Rainbow Birthday Cake

Preheat the oven to 350°F.
Prepare six 6-inch cake pans by spraying with nonstick spray and then lining the bottom with parchment paper. Set aside.
In the bowl of a stand mixer with the paddle attachment, combine the salted butter, canola oil and granulated sugar until well combined.
Add in the eggs, one at a time, mixing thoroughly between each addition.
Once mixed in, add the vanilla extract and butter flavor.
In a separate bowl, whisk together the cake flour, all-purpose flour, baking soda, baking powder and salt.
Add the dry ingredients to the mixer and slowly begin to incorporate. Once the dry ingredients are almost all combined with the wet ingredients, slowly pour in the buttermilk and mix until well combined and smooth.
Divide the batter evenly into 6 bowls. Color each bowl your desired color– I did pink, purple, blue, green, yellow and orange.
Pour the colored batter into the prepared pans.
Bake at 350°F for 20-25 minutes or until the edges of the cake start to pull away from the sides of the pan. Do not underbake or the cake will collapse.
Allow the cakes to cool on the counter for 10 minutes before flipping the cake out onto a cooling rack. Allow the cakes to cool completely and then freeze for 15 minutes before trimming.
To trim your cakes, use a sharp knife and cut the hard edge off of the outside of the cake. Next, use a long serrated knife to cut the top of the cake flat and to remove the browned portion on the bottom of the cake. This will make the final cake look much cleaner. Repeat with all 6 layers.
Freeze again while making the vanilla buttercream.

Making the Buttercream & Assembling the Cake

To make the buttercream, whip the butter in a stand mixer on high speed for 10-15 minutes. The butter should turn a very bright white color and will be very fluffy when it is ready for the next step.
Scrape the sides of the bowl and then add the powdered sugar in a few additions, mixing between each.
Add the vanilla and whip until smooth.
To arrange the cake, place a small dollop of frosting on your cake plate or stand to keep the cake in place. Set the first cake layer down in the center.
Spread an even layer of frosting on top using an offset spatula. Place the next layer on top and gently press down. Repeat until all layers have been added.
Spread a thin layer of frosting over the entire cake to trap the crumbs (called a crumb coat) and then chill in the freezer for 5-10 minutes.
Apply the rest of the frosting in a thicker layer, smoothing with an offset spatula or bench scraper. I added the sprinkles to the remaining frosting before applying to my cake. Make sure to set aside enough white frosting for the swirl on top, if desired.
Decorate the top with additional frosting or sprinkles, if desired.
Store in the fridge until 30 minutes before serving. Enjoy!

A slice of rainbow cake on a plate. All colors displayed.

How should I store my cake with rainbow design?

After you have assembled your cake, store in the fridge for up to 2 days. Remove from the fridge 30 minutes prior to serving. Enjoy!

A slice of rainbow birthday cake on a plate. In the background the res t of the cake is on a tray.

Rainbow Faves

Rainbow Layer Cake

5 from 1 vote

Print Pin Rate

Prep Time: 2

Cook Time: 25

Servings: servings

Calories: 617kcal

Ingredients

1/2 cup salted butter, melted
1/2 cup canola oil
2 cup granulated sugar
4 eggs, room temperature
1 tbsp vanilla extract
1/2 tsp butter flavor
2 cup cake flour
1/2 cup all-purpose flour
1/2 tsp baking soda
1/2 tsp baking powder
1 tsp salt
1 1/3 cups buttermilk, room temperature
Food coloring (gel works best)

Vanilla Buttercream

2 1/2 cups salted butter softened
4 1/2 cups powdered sugar
1 tbsp + 1 tsp clear vanilla
1/4 cup rainbow colored sprinkles

Instructions

Preheat the oven to 350°F.
Prepare six 6-inch cake pans by spraying with nonstick spray and then lining the bottom with parchment paper. Set aside.
In the bowl of a stand mixer with the paddle attachment, combine the salted butter, canola oil and granulated sugar until well combined.
Add in the eggs, one at a time, mixing thoroughly between each addition.
Once mixed in, add the vanilla extract and butter flavor.
In a separate bowl, whisk together the cake flour, all-purpose flour, baking soda, baking powder and salt.
Add the dry ingredients to the mixer and slowly begin to incorporate. Once the dry ingredients are almost all combined with the wet ingredients, slowly pour in the buttermilk and mix until well combined and smooth.
Divide the batter evenly into 6 bowls. Color each bowl your desired color- I did pink, purple, blue, green, yellow and orange.
Pour the colored batter into the prepared pans.
Bake at 350°F for 20-25 minutes or until the edges of the cake start to pull away from the sides of the pan. Do not underbake or the cake will collapse.
Allow the cakes to cool on the counter for 10 minutes before flipping the cake out onto a cooling rack. Allow the cakes to cool completely and then freeze for 15 minutes before trimming.
To trim your cakes, use a sharp knife and cut the hard edge off of the outside of the cake. Next, use a long serrated knife to cut the top of the cake flat and to remove the browned portion on the bottom of the cake. This will make the final cake look much cleaner. Repeat with all 6 layers.
Freeze again while making the vanilla buttercream
To make the buttercream, whip the butter in a stand mixer on high speed for 10-15 minutes. The butter should turn a very bright white color and will be very fluffy when it is ready for the next step.
Scrape the sides of the bowl and then add the powdered sugar in a few additions, mixing between each.
Add the vanilla and whip until smooth.
To arrange the cake, place a small dollop of frosting on your cake plate or stand to keep the cake in place. Set the first cake layer down in the center.
Spread an even layer of frosting on top using an offset spatula. Place the next layer on top and gently press down. Repeat until all layers have been added.
Spread a thin layer of frosting over the entire cake to trap the crumbs (called a crumb coat) and then chill in the freezer for 5-10 minutes.
Apply the rest of the frosting in a thicker layer, smoothing with an offset spatula or bench scraper. I added the sprinkles to the remaining frosting before applying to my cake. Make sure to set aside enough white frosting for the swirl on top, if desired.
Decorate the top with additional frosting or sprinkles, if desired.
Store in the fridge until 30 minutes before serving. Enjoy!

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2 Comments

Jessica says:

May 18, 2025 at 9:38 pm

This cake was AMAZING! it turned out perfect and tasted even better! will be making again!

Anna says:

December 21, 2025 at 10:59 pm

Hi,
If there is no cake flour available what would be the proportion for all purpose flour?