There’s nothing happier than a rainbow cake! Cake layer in rainbow hues are hidden behind a wall of rainbow licorice twists and Swiss meringue buttercream.
Here’s a dose of happy color for your Friday! I love rainbow cakes, so I was surprised to realize that I’d never made a rainbow layer cake for this blog. I’ve made Rainbow Frosted Cupcakes and Lemony Rainbow Checkerboard Cake, but somehow the original version has eluded my recipe index.
Hopefully I’ve made up for the exclusion (in spades!) with this cake’s interior and exterior rainbow colors.
This recipe makes a tall 8-inch round cake. It’s covered in Swiss meringue buttercream, which can be tricky for beginners, so be sure to check out my tutorial here. If you’re not a fan of Swiss meringue buttercream (like my mom – c’mon MOM!) then you can substitute a basic confectioners’ sugar and butter version (like the one at the bottom of this post).
The rainbow exterior is a wall o’ Twizzler Twists in rainbow colors. You can find these in the candy aisle at the grocery store, or you can order the required 2 packages here. You can’t get much simpler as far as cake decorating goes. Just line the twists up in rainbow color order at an angle, or you can place them vertically for easier slicing. I served this cake by placing my knife between two Twizzler twists and cutting the cake at an angle. It made for some very interesting slices!
The top edge of the cake is lined with gummy bears in rainbow colors. Now. I’m a Haribo fan from waaay back, but I also love the Albanese brand. I keep a 5 pound bag of the latter on hand because I love how soft they are and also because there’s probably something psychiatrically wrong with me. But, whatever. I love gummies, okay?!
I picked up the ultra-cute lollipop candles at the grocery store. I can’t find them for purchase online, but they are made by Betty Crocker. If you can’t locate the candles, then I think this cake would also look cute decorated with the real thing: swirly candy lollipops standing upright in the middle of the cake.
This cake’s flavor reminds me of white cake; a simple but rich bakery-made birthday cake when frosted with Swiss meringue buttercream.
Be sure to pick up an extra two dozen eggs (!) while you’re grocery shopping. The rainbow cake requires 10 egg whites, and the Swiss meringue buttercream requires 12 egg whites.
Rainbow Candy Cake
Rainbow cake layers
- 6 1/2 cups/790 g cake flour not self-rising, sifted
- 3 tablespoons baking powder
- 1/2 teaspoon fine grain sea salt
- 2 1/4 cups/500 ml whole milk
- 2 tablespoons pure vanilla extract
- 1 1/2 cups plus 4 tablespoons/395 g unsalted butter room temperature
- 2 1/2 cups/490 g granulated sugar
- 10 large egg whites
- Wilton or Americolor gel food colors: red orange, yellow, green, blue, purple
Vanilla Swiss meringue buttercream
- 12 egg whites
- 2 1/2 cups/500g sugar
- 1/4 teaspoon salt
- 2 1/2 pounds unsalted butter softened
- 1 tablespoon clear vanilla extract
- 2 packages 12.4 ounces each Twizzler Rainbow Candy Twists
- 3 tablespoons rainbow sprinkles jimmies
- 36 gummy bears
- Make the cake layers: Preheat the oven to 350 degrees.
- Grease six 8-inch round cake pans, and line the bottoms with parchment. If you don’t have six pans (understandably so) use as many as you have, and plan to wash them between baking cake layers.
- Sift the flour, baking powder and salt into a large bowl. Combine milk and vanilla. Beat butter with a mixer on medium speed until smooth. With the mixer running, gradually add the sugar and beat until the mixture turns pale and fluffy, about 3 minutes.
- Reduce speed to low, and add the flour mixture in 3 additions, alternating with the milk. Begin and end with the flour mixture. Beat until just combined. Do not over-mix.
- Beat the egg whites in a clean mixer bowl on medium speed until stiff peaks form, about 5 minutes. Gently fold the egg whites into the batter in three additions.
- Place two cups of batter in six separate bowls. Tint each bowl of batter with each of the food colors until a vibrant hue is achieved (start with 1/2 teaspoon color and increase as needed). Fold the color in well with a rubber spatula until no streaks of white cake batter remains.
- Spread the batter into the prepared pans and bake for 18 to 20 minutes. Let the layers cool completely on a wire rack. Run a knife around the edges of the cakes and the pans before turning them out.
- Level the cakes with a serrated knife or a cake leveler so that the cakes are approximately 1 1/2 inches tall. Save the cake scraps for breakfast or snack on them now (smile).
- Make the frosting: Set a saucepan filled one-third full of water over medium-high heat and bring to a simmer.
- Whisk together the egg whites, sugar, and salt in a large heatproof bowl (I suggest a stainless steel bowl). Set over the simmering water and whisk until the mixture is hot to the touch and the sugar has dissolved (120-140 degrees on a candy thermometer, to be sure).
- Transfer the mixture to the bowl of a stand mixer fitted with the whisk attachment.
- Beat on low speed for 2 minutes. Increase to medium-high until stiff peaks are formed.
- Continue beating at medium-high speed until the mixture is fluffy and has cooled (the mixing bowl should feel cool to the touch).
- Turn the mixer off and switch from the whisk attachment to the paddle. Turn the mixer on medium-low and add the butter, a few cubes at a time, beating until well incorporated before the next addition.
- Add the vanilla extract. Beat until the frosting on high speed until it is thick and completely smooth.
- Important note about Swiss buttercream frosting! After a few pieces of butter are added to the whipped whites, the mixture will deflate. It may look like soup or even look curdled – do not let this discourage you. This is just one ugly stage the buttercream must pass through before becoming fluffy whipped frosting.
- Frost the cake: Transfer 2/3 cup of frosting to a piping bag fitted with a small star tip; set aside.
- Fill each cake layer with 1/3 to 1/2 cup of the frosting. Begin with the purple cake layer on the bottom, followed by the blue, green, yellow, orange and red. Cover the entire cake with frosting using an off-set spatula.
- Decorate! Place a red Twizzler twist against the cake at a 45° angle so that it sticks to the frosting (you can also stand them vertically and trim the tops if you wish). Continue with an orange, green, blue, and purple twist. Carry on in this manner until the cake is completely covered. You will have 3-ish leftover twists left over (snack on them or save for another use). Use the reserved piping bag of frosting to pipe small stars along the top edge of the cake. Position the decorator nozzle so that the icing also covers the tops of the candy twists; Sprinkle top of cake with rainbow jimmies. Place gummy bears upright in the frosting stars at the top edge of the cake in rainbow order. Add candles to the center of the cake, if appropriate for your celebration.
- How to slice: Cut the cake with a large chef’s knife at an angle between twizzler twists.
- Cover the leftover cake loosely with plastic wrap and store at room temperature.