This fabulous rainbow layer cake is a stunning cake for nearly any occasion, from a childhood birthday to a celebratory pride party in June. It’s easier to make than it looks but it does require you to bake 6 different layers. If you don’t have 6 cake pans (and who does?) just bake it in batches. You can see my section above on tips on baking in batches. To get the vivid layers of color, use gel food coloring a not grocery store liquid food coloring. My favorite brand is AmeriColor, but any professional grade gel food coloring will work. Liquid food coloring just won’t give you the same color. Gel food coloring can be found at the craft stores like Michaels, JoAnn, or online.
Frosting Chilling Time 1 hourhour30 minutesminutes
Servings 12
Calories 948kcal
Author Irvin
Ingredients
Cake batter
1 1/4cupunsalted butter at room temperature285 g or 2 1/2 sticks
2 1/2cupswhite sugar500 g
1tablespoonclear imitation vanillaor real vanilla
1 1/2tablespoonbaking powder
1teaspoonkosher salt
1/4teaspoonbaking soda
4large eggs
2large egg whites
3 1/2cupscake flour455 g
1 1/2cupsbuttermilkwell shaken
Coloring
1/4teaspoonAmeriColor Gel Regal Purple
1/4teaspoonAmeriColor Gel Royal Blue
1/4teaspoonAmeriColor Forest Green
1/4teaspoonAmeriColor Gel Lemon Yellow
1/4teaspoonAmeriColor Gel Orangeplus 1 to 2 drops of Super Red (optional)
1/2teaspoonAmeriColor Gel Super Red
Frosting
12ounceschopped dark bittersweet chocolate340 g
1 1/4cupsheavy cream290 g
1 1/4cupswhite sugar250 g
1 1/2teaspoonvanilla extractreal or clear
10tablespoonssalted butterif unsalted add 1/2 teaspoon kosher salt, 140 g or 1 1/4 sticks
To finish
Rainbow sprinklesoptional
Instructions
Preheat the oven to 350°F.Spray six 8-inch cake pans with cooking oil, then line the bottom of the pans with parchment paper. If you don’t have six cake pans, see the section above about baking in batches.
Place the butter, sugar, vanilla, baking powder, salt, and baking soda in the bowl of a stand mixer fitted with a paddle attachment. Start the mixer on low, slowly bringing the mixer up to medium speed as the butter becomes more pliable and the sugar is incorporated. Mix for 5 or 6 minutes, or until the butter and sugar are fluffy and light in color. Scrape down the sides of the bowl once or twice while you cream the ingredients.
Scrape down the sides of the bowl then add the eggs, one at a time, scraping down the sides between additions. Add the egg whites beating to incorporate. Don’t worry if the batter looks broken as you add eggs. That’s normal.
Add half the flour and slowly stir it in with the mixer. Scrape down the sides, add the buttermilk, scrape down again, and then add the remaining flour.
Divide the batter into 6 different bowls. This will be about scant 1 1/2 cups of batter, or about 300 grams each if you have a scale. Mix in the food coloring to each bowl with a spoon or spatula. Note that to achieve the right shade orange, I added a drop of red food coloring gel to the orange layer, but you might want to skip that if you like the way the orange gel comes out.
Scrape and pour the batter into the pans, spreading the cake batter evenly into the pan. It will be a thin layer. Bake for 15 to 17 minutes, or until a toothpick inserted comes out clean, the top of the cake springs back when you gently press it with your fingers, and the cake starts to pull away from the sides of the pan.If you don't have 6 pans or you can't fit them all in the oven, see my section above for baking the cake layers in batches.Let the cakes cool in the pan for 15 minutes, then run a thin knife, spatula or plastic dough scraper around the side of the pan, then carefully release the cake layer onto a cooling rack. Peel away the parchment paper. Let cool completely before frosting.
While the cake layers are baking, make the frosting by placing the chocolate in a large microwave safe bowl. Microwave for 30 seconds, stir, and microwave for an additional 30 seconds. The chocolate will not be melted but the bowl will be warm, and the chocolate touching the bowl will be melty.
Place the cream, sugar and vanilla in a medium pot and heat on the stove on medium heat stirring frequently, until the sugar has dissolved, and the cream is heated. Bubbles should start to form on the side of the pot. Do not let it boil.Pour into the bowl of chocolate and stir until the chocolate is melted.
Add the butter to the melted chocolate, 1 or 2 tablespoons at a time, stirring until the butter is melted and incorporated.
Cover with plastic wrap and place in the refrigerator for 1 to 2 1/2 hours. Stir halfway through chilling the frosting. You want the frosting to be cool enough to be spreadable like peanut butter or Nutella, but not too thick or stiff. If it’s too stiff, stir it and let it sit on the counter at room temperature for 5 to 10 minutes to warm up a bit.
Once the cake layers are cooled, and the frosting is the right thickness, place a small dab of frosting on a cake plate or pedestal and place the purple layer on it. Frost a thin layer of chocolate frosting all over the top of it, then add the blue layer. Repeat this process, frosting the cake layers, adding the green, yellow, orange and then red on top. Frost the sides and top with the remaining frosting.Press a small amount of rainbow sprinkles around the bottom edge of the cake before serving.