Rainbow Cake
This Rainbow Cake showcases a graceful cascade of vibrant cake layers beneath a delicate veil of white Swiss meringue buttercream.
This Rainbow Cake showcases a graceful cascade of vibrant cake layers beneath a delicate veil of white Swiss meringue buttercream.
- 1
- 1 1/2
- 3
- 2
- 6
- large egg whites room temperature
- 2/3
- cup whole milk room temperature
- teaspoons vanilla extract
- cups (12 ounces) cake flour
- cups (10 1/2 ounces) sugar
- 4
- teaspoons baking powder
- teaspoon salt
- 16
- tablespoons unsalted butter cut into 16 pieces and softened
- 7
- egg whites
- cups sugar
- teaspoon salt
- 6
- sticks (2 1/2 cups) unsalted butter at room temperature, cut in to 24 pieces
- 1 teaspoon
- vanilla extract
- Carbohydrate 88.0964983471638 g
- Cholesterol 156.8 mg
- Fat 64.5561204196486 g
- Fiber 14.5790725218811 g
- Protein 43.1918789379299 g
- Saturated Fat 39.1847754646974 g
- Serving Size 1 1 Recipe (870g)
- Sodium 6061.56718426805 mg
- Sugar 73.5174258252826 g
- Trans Fat 4.05537513673388 g
- Calories 1071 calories
Step-by-step
- Adjust oven rack to middle position and heat oven to 350 degrees. Grease six 9-inch round cake pans, line with parchment paper and grease parchment.
- Whisk together egg whites, milk, and vanilla in bowl.
- Using stand mixer fitted with paddle, mix flour, sugar, baking powder, and salt on low speed, about 30 seconds. With mixer running, add butter, 1 piece at a time, until incorporated and mixture resembles moist crumbs. Add all BUT 1/2 cup egg mixture and mix until just combined. Increase speed to medium-high and beat until light and fluffy, about 1 minute. Add remaining 1/2 cup egg mixture in slow stream. Scrape down bowl and beat on medium-high speed until well combined, about 15 seconds.
- Divide batter evenly in to six bowls.
- Add about one teaspoon of gel food color paste to each bowl and mix thoroughly so the color is evenly distributed. Pour batter in to prepared pans and smooth tops with rubber spatula. Bake until toothpick inserted in center comes out clean, about 11 minutes.
- Let cakes cool in pans on wire rack for 10 minutes. Remove cakes from pans, discarding parchment, and let cool completely on rack, about 30 minutes.
- Place sugar, egg whites and salt in the heat-proof bowl of an electric mixer. Set bowl over a pan of gently simmering water, and whisk until sugar has dissolved and egg whites are hot to the touch, about 3 minutes. Test by rubbing the mixture between your fingers; it should feel completely smooth.
- Transfer bowl to mixer stand. Using the whisk attachment, beat on high speed until mixture has cooled completely and formed stiff and glossy peaks, about 10 minutes.
- Add the butter, one piece at a time, and beat until incorporated after each addition. Don't worry if the buttercream appears curdled after all the butter has been added; it will become smooth again with continued beating. Add vanilla extract, and beat just until combined.
- Place the purple layer on a cake plate or cardboard round. Spread 1 1/2 cups of buttercream evenly over the cake with an offset spatula. Repeat process with blue, green, yellow, orange and red, filling with buttercream between each layer.
- Crumb coat the cake by applying a thin layer of frosting over the entire cake and chill for 30 minutes. Then use the remaining buttercream to frost the cake. Using a large offset spatula smooth the sides and top of the cake. Refrigerate cake.
- Before serving let it sit at room temperature for at least 2 hours.
Why does the buttercream suddenly look like curdled scrambled eggs halfway through whipping? This startling visual breakdown happens when chilled butter is introduced to a meringue whose temperature has dropped too low, preventing the fat emulsion from forming correctly. Understanding the thermodynamic thresholds of sugar, egg whites, and dairy transforms a potentially disastrous baking project into an exercise in reliable kitchen chemistry.
Achieving Uniform Layers and Even Baking
Dividing batter among six individual pans requires precision to avoid uneven baking times that dry out thinner layers while leaving thicker ones raw in the center. Cake flour, with its lower protein content compared to all-purpose flour, yields the tender crumb necessary for this structure, but it also demands exact measurement so the delicate crumb does not collapse under its own weight. Weighing the total batter on a digital scale and dividing that exact mass by six ensures each tier bakes at the exact same rate in roughly 11 minutes at 350 degrees Fahrenheit. Spreading the colored batter with a rubber spatula into greased, parchment-lined pans prevents sticking, while letting the baked rounds cool completely on wire racks for 30 minutes stops residual steam from softening the crust before frosting.
Mastering Swiss Meringue Buttercream
Swiss meringue buttercream relies on thermal energy to dissolve granulated sugar completely into egg whites over simmering water until the mixture reaches a hot-to-the-touch tactile cue of approximately 160 degrees Fahrenheit, which pasteurizes the whites and creates a stable protein network. Whipping this hot mixture on high speed for 10 minutes cools the bowl thoroughly and builds stiff, glossy peaks before any fat is introduced. Adding the softened unsalted butter one piece at a time guarantees that the emulsifiers in the egg whites can successfully suspend the heavy fat load. If separation does occur, continuous mechanical agitation or gently warming the exterior of the bowl brings the emulsion back together into a smooth, spreadable frosting. Pair slices of this rich dessert with strong, unsweetened black coffee or bracingly tart citrus tea to cut through the density of the butter and sugar.
