Nothing will make you smile quite like this six-layer rainbow cake. The secret to this cake’s vibrant colour is to use gel food colouring — it really makes each layer pop. For an easy decorating technique, we love the “naked cake” look, which involves gently scraping frosting off of the cake for a rustic, hassle-free result. However you decorate this cake, though, it’s sure to turn some heads.
Naked Six-Layer Rainbow Cake
Total Prep and Baking Time: 2 hours 30 minutes
For the Cake:
5 cups all-purpose flour
1 tablespoon + 2 teaspoons baking powder
1 teaspoon kosher salt
2 cups butter, room temperature and cubed
3 cups granulated sugar
¾ cup vegetable oil
2 teaspoons vanilla extract
2 cups whole milk
6 egg whites, whipped separately
Food colouring (six different colours of your choice)
For the Butter cream Frosting:
3 cups unsalted butter
5 cups powdered sugar
2 teaspoons vanilla extract
1. Preheat your oven to 350 degrees F. Grease and line six 8-inch cake pans. Set aside.
2. Whisk together your flour, baking powder, and salt. Set aside.
3. Beat together your butter and sugar until creamed, about 3 minutes. Add in your 2 eggs and beat until well combined, scraping down the sides of the bowl as needed. Add in your vegetable oil and vanilla and beat until combined.
4. Add in ⅓ of your flour and mix until combined, then pour in half of your milk, mixing until combined. Continue with another ⅓ of your flour, followed by the rest of your milk, and then mix in the rest of your flour.
5. In a separate bowl, whisk your egg whites until frothy and fluffy. Fold the egg whites into your batter with a wooden spoon.
6. Divide your batter into six different bowls, then add food colouring to each one until you achieve your desired colour. Mix to combine, then pour the batter into your prepared pans. Bake for 20-25 minutes, until set. Let the cakes cool completely (you can put them in the fridge to speed this up), then run a knife around the outside of the cakes to loosen them and remove them from the cake pans.
7. To make your butter cream, beat together your frosting ingredients until smooth. Taste and add more sugar or vanilla if needed.
8. When you’re ready to decorate, place a dollop of frosting on your work surface to secure your first layer of cake. Level off your first layer with a serrated knife, then spread a layer of your frosting over the cake. Place your next layer on top, press down slightly once it is centered, and repeat, continuing with all of your layers. For the final layer, level off the top and lightly frost the top and sides of the cake with your first layer of frosting, known as a “crumb coat.” You don’t have to worry about crumbs at this point – you’re going to cover them up soon! Refrigerate for at least 15 minutes, or up to an hour.
9. When you’re ready, take the cake out again and finish frosting with your final layer – don’t be afraid to lay it on thick. Using a bench scraper or cake leveler, scrape off the frosting you just applied for a flat, “naked” look. Top the cake with sprinkles. This will keep well, in a cake saver, in the fridge for up to 3 days.
Story and editing by Sydney Kramer, Kristen Griffin, and Eloise Kirn
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