Rainbow Sheet Cake Recipes

RAINBOW CAKE

Steps:

• Preheat the oven to 375 degrees F. Spray the bottom and sides of six 8-inch round cake pans; dust with flour and tap out excess.
• Whisk together the flour, baking powder and salt in a medium bowl; set aside.
• Beat the butter, sugar and oil in a large bowl with an electric mixer on medium-high speed until light in color and fluffy, about 5 minutes. Beat in the eggs, one at a time, then the vanilla seeds, until combined.
• Transfer the creamed mixture to a very large mixing bowl, then alternate folding in the flour mixture and the milk with a spatula, adding the flour in 3 additions and the milk in 2, starting and ending with the flour, just until smooth. Divide the batter equally among 6 mixing bowls. Using gel food colors, tint each bowl with one of the colors of the rainbow. Pour each color into its own prepared cake pan.
• Bake, rotating the pans halfway through, until a toothpick inserted in the centers comes out clean, 18 to 20 minutes. Cool the cakes in the pans on a rack for 10 minutes, then remove the cakes to the rack to cool completely.
• Level the tops of any cake layers that have domed by slicing the domes off with a serrated knife. Put some buttercream into a pastry bag fitted with a large round tip. Put the bottom cake layer onto a cake plate. Pipe around the edge of the cake layer to create a frosting "dam." Fill the center with a thin layer of jam (about 1/2 cup). Top with another cake layer and repeat until you have stacked and filled all the layers. Frost the outside of the cake with the remaining buttercream and decorate as desired.
• In the bowl of a stand mixer, combine the confectioners' sugar, butter, milk, vanilla seeds and salt. Beat on low speed for a while. When the sugar is incorporated, turn the speed up and beat until the buttercream is fluffy and smooth. If it's too wet, add a bit more confectioners' sugar. If it's too stiff, add a bit more butter. Be sure to scrape the sides of the bowl once or twice to make sure everything is combined.
• Use immediately or store in an airtight container at room temperature for up to 24 hours or in the fridge for up to 2 weeks. Rewhip cold buttercream before using.

RAINBOW VERTICAL CAKE

Steps:

• For the cake: Arrange an oven rack in the middle of the oven and preheat the oven to 350 degrees F. Spray two 18-by-13-inch half-sheet pans with baking spray and line with parchment. Coat with baking spray and dust with flour, knocking out any extra.
• Whip the egg yolks with 1/2 cup of the granulated sugar and vanilla in a medium bowl using an electric mixer on medium-high speed until thick ribbons form, about 5 minutes. Transfer to a large bowl and rinse and dry the bowl. Add the egg whites and salt and whip on medium high speed until foamy, about 1 minute. With the machine still going slowly add the sugar and beat until glossy stiff peaks form, about 5 minutes. Using a large spatula fold the egg whites in to the yolks until well combined. Add a quarter of the flour and fold it until combined. Repeat 3 more times until all the flour is added.
• Divide the batter evenly between the 2 prepared pans. Bake until lightly springy when touched, about 12 minutes.
• Dust 2 clean large kitchen towels with the confectioners' sugar and flip the cakes out onto the towels with the short sides facing you. Working with 1 cake at a time, remove the parchment and roll up each cake starting from the short end. Set aside to cool.
• For the frosting: Bring a few inches of water to a boil in a saucepan that can hold the heatproof bowl of a stand mixer above the water.
• Add the granulated sugar, lemon juice, salt and egg whites to the stand mixer bowl and whisk together by hand. Set the bowl above the boiling water and whisk until the mixture is warm to the touch and the sugar is completely dissolved. Transfer to the stand mixer fitted with the whisk attachment and beat at medium-high speed until cool and the whites hold stiff peaks, 10 to 15 minutes.
• Continue to beat, tossing in the butter a couple of chunks at a time, making sure the pieces are incorporated before adding more. After all the butter is incorporated continue whisking on medium-high speed. The mixture will deflate and appear curdled. Continue whisking until the buttercream comes back together with a smooth and spreadable consistency, about 5 minutes. Slowly drizzle in the vanilla while beating until smooth and light, about 5 minutes more. (If the frosting is very soft or begins to break, refrigerate until set but still spreadable and then beat until light before using.)
• Transfer 3/4 cup of the frosting to six small bowls. Color them red, orange,, yellow, green, blue and purple and transfer them to piping bags and set aside. Cover the remaining white frosting and set aside.
• To assemble: Unroll the cooled cake layers so they lay flat. Transfer the cakes to a cutting board using a serrated knife to divide each cake in half lengthwise, creating 2 long strips of cake (4 total). Starting ¼-inch from the top of each piece of cake pipe an even line of red frosting lengthwise on each piece. Repeat with the remaining colors.
• Take one strip of frosted cake and roll it into a tight jelly roll. Add another strip of cake, matching the ends and coiling it around the center roll as you would a cinnamon roll; repeat with the remaining cake strips, trimming the ends to fit as necessary. Chill in the refrigerator for 30 minutes.
• Trim the ends of the cake so they are flat and transfer to a cake board or platter, standing the cake up on one end and securing it to the surface with a dollop of the reserved white frosting.
• Spread a thin layer of the white frosting over the top and sides of the cake for a crumb coat. Chill the cake in the refrigerator for 30 minutes to set the coat.
• Frost the cake with the remaining white frosting, using an offset spatula to create swirls if desired. Decorate the top edge of the cake with sprinkles as desired.

RAINBOW PETAL SHEET CAKE

Steps:

• Heat oven to 350°F (325°F for dark or nonstick pans). Grease bottom only of 1 (13x9-inch) pan. Make cake mix as directed on box using water, oil and eggs.
• Bake 28 to 32 minutes or until a toothpick inserted in center comes out clean. Cool 10 minutes in pan; remove from pan to cooling rack. Cook completely, about 1 hour.
• Meanwhile, beat butter with an electric mixer on low speed until creamy. Beat in the powdered sugar, 1 cup at a time, until smooth. Add vanilla and milk, 2 tablespoons at a time until well combined. If frosting is too thick, beat in more milk.
• Use 1/2 cup frosting to frost a thin layer over entire cake. Divide remaining frosting into four bowls (about 3/4 cup frosting in each bowl). Mix blue, purple, green and orange food color, one into each bowl, until desired hue is reached.
• Place each color in individual resealable food-storage plastic bag. Cut 1/2 inch off one corner of each bag. Pipe a dot of blue frosting and use back of teaspoon to pull frosting slightly. Repeat with remaining colors, alternating colors as you cover cake, slightly overlapping dots of frosting.

RAINBOW CAKE

Steps:

• Heat the oven to 350 degrees. Lightly grease three 9-inch round cake pans with nonstick cooking spray, then add a couple tablespoons of flour to each pan. Shake and rotate each pan until the flour fully coats the inside. Discard the excess flour.
• In a medium bowl, whisk the 3 2/3 cups flour with the baking powder and salt to combine. In a separate medium bowl, whisk the egg whites vigorously until lightly foamy, about 1 minute. Add the milk and whisk to combine.
• In the bowl of an electric mixer fitted with the paddle attachment, cream the sugar, oil and butter on medium speed until light and fluffy, 4 to 5 minutes, scraping down the sides as needed. Reduce the speed to low. Add the vanilla extract and mix to combine.
• Add a quarter of the flour mixture to the bowl and mix on low speed until combined. Add a third of the egg white mixture and mix until combined. Continue to add the dry and wet ingredients, alternating until both are fully incorporated and the batter is smooth, scraping the sides as needed.
• Divide the batter evenly among the three cake pans. (You'll want about 2 1/3 cups/575 to 600 grams of batter in each pan.) Spread the batter in each pan into an even layer. Bake until the surface is evenly golden brown, the cake appears to have pulled away from the pan at the top edges and the center of the cake springs back gently when touched, 30 to 35 minutes.
• While the cakes bake, make the frosting: In a medium saucepan over medium heat, combine the milk with 1/2 cup/100 grams granulated sugar, stirring occasionally, until the mixture comes to a simmer. Meanwhile, whisk the remaining 1 cup/200 grams granulated sugar with the cornstarch and salt in a large bowl until combined. Add the egg yolks and whisk until smooth.
• Pour about 1 cup of the hot milk into the yolk mixture and whisk to combine. Add the yolk mixture to the saucepan and whisk to combine. Reduce the heat to low. Cook, stirring constantly with a silicone spatula, until it thickens enough to coat the back of the spatula, 3 to 5 minutes.
• Strain the mixture through a fine-mesh sieve into a medium heat-safe bowl. Cover the surface directly with plastic wrap or a wet paper towel and refrigerate until no longer warm, about 1 hour. If making the piped version, make a separate half-batch of the custard now (see Tip 2).
• When the cakes are baked, cool them in the pan for 10 minutes, then invert them onto a cooling rack to cool completely.
• When the custard has cooled, finish the frosting: Transfer the custard to the bowl of an electric mixer fitted with the whip attachment, and beat on medium speed until smooth, about 1 minute. With the mixer running and a splash guard attached or a kitchen towel draped over your mixer to contain splashes, add the butter about 2 tablespoons at a time, mixing until the butter is combined between each addition, about 20 seconds.
• Increase the speed to medium-high. The mixture may look uneven and lumpy, but keep whipping until it becomes silky smooth and lightens in color, 5 to 7 minutes. Add the vanilla and mix to combine. (If making the piped version, finish the extra half batch of frosting now. Combine batches before dividing, coloring and frosting.)
• Use a serrated knife to slice each cake horizontally into two even rounds to form six cake layers: Place the first cake on a cake decorating turntable or flat plate. Use the knife to cut into the cake by holding the knife horizontally with the sharp side facing the cake, halfway up the side of the cake. Lightly cut into the cake by slicing into the outer perimeter of the cake all the way around, rotating the turntable or plate as you score it. Once you've created a marker around the outside of the cake as a visual guideline, continue rotating and moving the knife deeper into the cake to divide the cake into two even layers. Repeat with the other two cakes.
• Evenly divide the frosting into six bowls (you should have about 1 1/4 cups each). Use food coloring gel or paste to color the frosting red, orange, yellow, green, blue and purple. Start with a few drops and add more as needed. Mix thoroughly.
• Working with one cake round on the cake decorating turntable or flat plate, use a pastry brush to brush away any extra crumbs that have collected before frosting. Scrape about 1/3 cup red frosting on top of the cake layer, in the center, and use a medium offset spatula to spread it into an even layer, spreading it all the way to the edge of the cake. Wipe the spatula clean. Top with another layer of cake, bottom-side up, then scrape about 1/3 cup orange frosting on top of the cake layer, in the center, and spread into an even layer. Continue this process, spreading three more cake layers with 1/3 cup of the yellow, green and blue frostings and wiping the spatula clean after each application. Top with the final cake layer, bottom-side up. (You'll use the purple frosting later.)
• Run a clean offset spatula around the sides of the cake to flatten the edge and smooth out excess frosting between layers that has leaked out on the sides. Refrigerate for 20 minutes to help the frosting set.
• Starting at the bottom of the cake, use a small offset spatula to apply a 1-inch thick stripe of red frosting. Wipe the spatula clean and repeat this process just above the red frosting with the orange frosting. Repeat, wiping the spatula clean between each application, with the yellow frosting, green and blue. The blue should be at the top edge of the cake and around the outer edge of the top surface of the cake. Cover the remaining top of the cake with the purple frosting. (If making the piped version, refer to Tip 3.)
• Hold a clean spatula horizontally flush against the top surface of the cake and slowly rotate the cake to smooth the surface. Clean the spatula and do the same to the sides of the cake, holding the spatula vertically. The colors will blend together to create an ombré effect. Add extra frosting to fix smudges and smooth the surface again. If desired, chill another 15 minutes before serving (this will make it easier to slice).

RAINBOW LAYER CAKE

Steps:

• Heat oven to 350°F. Spray 3 (8-inch) round cake pans with cooking spray.
• In large bowl, beat cake mix, water, oil and eggs with electric mixer on low speed 30 seconds, then on medium speed 2 minutes, scraping bowl occasionally. Divide batter evenly among 6 small bowls, about 1 1/3 cups each.
• Using food colors, tint batter in 1 bowl blue, 1 bowl red, 1 bowl green, 1 bowl yellow, 1 bowl orange (using red and yellow) and 1 bowl purple (using blue and red).
• Refrigerate 3 colors of batter until ready to bake. Pour remaining 3 colors of batter into cake pans.
• Bake 18 to 20 minutes or until cake springs back when touched lightly in center and begins to pull away from side of pan. Cool 10 minutes. Remove from pans to cooling racks; cool completely.
• Wash cake pans. Bake and cool remaining 3 cake layers as directed.
• In large bowl, beat shortening and butter with electric mixer on medium speed until light yellow. On low speed, gradually beat in powdered sugar. Beat in vanilla. Add milk, 1 tablespoon at a time, beating until frosting is smooth. Beat on high speed until light and fluffy.
• Trim rounded tops off cakes to level, if needed. On serving plate, place purple cake layer. Spread with frosting to within 1/4 inch of edge. Repeat with blue, green, yellow, orange and red cake layers. Spread light coat of frosting on top and side of cake to seal in crumbs, then frost with remaining frosting.

RAINBOW SHEET CAKE

Steps:

• Make cake batter according to box directions.
• Separate prepared batter into small bowls. You should have 6-8 bowls full of batter.
• Mix 10-12 drops of food coloring into 1 small bowl of batter. Mix thoroughly to blend color. Repeat with the different bowls, creating different colors.
• Grease rectangular cake pan. Pour 1 bowl full of batter into corner of the pan, Taking next bowl full, pour next to the first color. Continue with additional colors until bottom of pan is covered.
• Repeat the above process with the second layer. Don't worry about the colors mixing. As long as you simply pour the batter on top of, or next to the other color, it will be okay.
• When finished, cook cake according to box directions. When done, cool thoroughly.
• FOR FROSTING: Make the instant pudding only using half as much milk as called for. Place in refrigerator until set. The pudding will be very thick. Fold in Cool Whip and blend well. Spread over cooled cake.

EASY SIX-LAYER RAINBOW CAKE

Steps:

• Preheat the oven to 400 degrees F (200 degrees C). Grease six 9-inch round cake pans and dust with flour.
• Sift together the flour, baking powder, and baking soda.
• Beat 3/4 cup plus 2 tablespoons butter, milk, sugar, egg whites, and vanilla extract in a large bowl with an electric mixer until smooth. Stir in flour mixture and mix until just combined.
• Divide cake batter evenly between 6 bowls. Mix in different food coloring to each bowl, creating 6 different colored batters. Start with just 1 to 2 drops of food coloring in each bowl, then mix; you can always add more.
• Bake each cake in the preheated oven, until a toothpick inserted in the center comes out clean, 15 to 20 minutes. Set aside to cool.
• Beat cream in a chilled glass or metal bowl with an electric mixer until stiff peaks form. Stir together confectioners' sugar and mascarpone cheese in a separate bowl, then fold gently into the whipped cream until smooth.
• Spread frosting on each layer of cooled cake, placing one on top of the other. Cover the top and sides with the remaining frosting. Refrigerate for 2 hours before serving.