How I Made the Viral Rainbow Layer Cake

Impress (and delight!) partygoers with a colorful layered rainbow cake.

How I Made the Viral Rainbow Layer Cake

By now, you might've seen the video of me making my daughter's birthday cake. Every year, we let our kids choose what kind of cake they want for their party, and this year my little one immediately asked for rainbow, in proper order. I looked around for rainbow cakes to order nearby, which were 1) way more expensive than I thought they would be, and 2) not homemade. As someone whose love language is creating delicious treats for those I love, the second point was more offensive than the first. And as a baker, why wouldn't I make the cake myself?

So I got to work. Because I needed six layers of cake in six different colors, I used If You Care pans, allowing me to bake all of the layers at once (plus, I could skip the steps of lining all of my cake pans AND clean up was a breeze). I used my favorite vanilla cake recipe (below) with rainbow food coloring and many, many rainbow sprinkles. Everyone at the party loved it—I highly recommend and can't wait to see what you make!

Ingredients for Rainbow Layer Cake

For the cake - all ingredients at room temperature

• 2 sticks unsalted butter
• 2 cups sugar
• 3 cups all-purpose flour
• 2 teaspoons vanilla extract
• 4 large eggs
• 2 teaspoons baking powder
• 1/4 teaspoon sea salt
• 1 ¾ cups whole milk

For the simple syrup

• 1 cup sugar
• 1 cup water
• 1/2 teaspoon vanilla extract
• Pinch of salt

For the icing

• 2 sticks unsalted butter, at room temperature
• 1 teaspoon vanilla extract
• 3 ¾ cups confectioner's sugar
• 1/4 teaspoon sea salt

How to Make a Rainbow Layer Cake

1. Preheat your oven to 350ºF.

2. Using a hand-mixer or electric stand mixer with a paddle attachment, beat the butter on high for 1 minute. Scrape down the sides of the bowl, then add sugar. Beat on high for 2 minutes.

3. Add the vanilla extract. Mix at medium-low speed and add eggs one at a time. Make sure to scrape down the sides of the bowl every so often.

4. In a separate bowl, stir together the flour, salt, and baking powder.

5. Use the lowest speed to add in half of the flour mixture. (Any faster and you’ll get a blowback of flour all over yourself.) When that’s fully incorporated, add half of the milk. Repeat with the remaining flour, then the remaining milk until the batter is smooth, being careful not to overmix.

6. Once the batter is made, divide it evenly into six bowls. Add food coloring to each—one pink, one orange, one yellow, one green, one blue, and one purple and mix well.
7. Pour the batter into the If You Care Pans and bake for 35-40 minutes, or until the cakes spring back slightly.
8. While the cakes bake, make the icing. Using a hand mixer or a stand mixer fitted with the whisk attachment, whip the butter on high for 1 minute. Add the vanilla and whip just to incorporate.
9. In a separate bowl, stir the sugar and salt together. With the mixer on low speed, add the sugar 1 cup at a time, until completely incorporated. Scrape down the sides of the bowl between additions. Whip on high speed for 3 minutes, until light and fluffy. Set aside.
10. Once the cakes are finished cooking, remove them from the oven and let them cool completely.
11. Make the simple syrup by heating the sugar, water, salt, and vanilla in a medium saucepan over medium-high heat. Cook until the sugar has dissolved completely. Let cool.
12. When the cakes are cool, level the cakes with a serrated knife so the tops are flat. Start with purple cake on the bottom. Drizzle about two teaspoons of simple syrup over the cake and spread a layer of icing over it. Stack the blue on top and repeat, then continue with green, yellow, orange, and pink.
13. Use an offset spatula to spread any icing that has come out of the sides of the cake around the outside and refrigerate for 30 minutes.
14. Remove the cake from the fridge and carefully trim the edges so they're all even. Spread a thin crumb coat of icing around the cake to lock in the crumbs and keep the cake stable. Refrigerate for another 30 minutes - one hour.
15. Remove the cake from the fridge and spread another layer of icing over the crumb coat, making it as smooth as possible.
16. Press rainbow sprinkles into the icing so the surface area is completely covered. You should be able to hold the sprinkles in your hand and press them in the icing as you move around the cake.
17. Decorate the sprinkles with any shapes or words you want, and get ready to be amazed when you cut into the cake. You did it!

What You’ll Need

• Six If You Care Pans

• Food Coloring

• Rainbow Sprinkles

• Serrated Knife

In a rut in the kitchen? Send me your cooking questions! Email askmelissa@bakedbymelissa.com for my cooking advice and insights, and don't forget to tag@bakedbymelissa on Instagram with pictures of your creations.