stacked rainbow cake

How To Make stacked rainbow cake

• 1

  You'll need two 8-inch round cake pans, one 6-inch-diameter oven-safe saucepan, one clean 28-ounce tomato can (label removed), and one cupcake pan. Line the bottoms of the cake pans, saucepan, and tomato can with parchment and coat with cooking spray. Use 2 1/2 cups cake batter in each cake pan, 2 cups in the saucepan, and 1 1/2 cups in the tomato can. Fill a cupcake paper in the cupcake pan half full of batter.
• 2

  Bake cakes at 350 degrees F until tops spring back when touched. Cupcake will bake in about 18 minutes, 8-inch cakes in about 30 minutes, and the tomato-can and saucepan cakes in 40 to 45 minutes. Allow to cool and remove from pans.
• 3

  Wrap cooled cakes in plastic wrap and chill 5 hours or overnight. When you're ready to decorate, remove parchment, trim domed tops, and slice each cake into two layers.
• 4

  Reserve about 3 cups buttercream for assembling cake layers. Divide remaining frosting among 10 bowls (we used about 1 cup each for the purple, blue, and teal, 3/4 cup each for the green and yellow, and 1/2 cup each for the reds, orange, and pink) and tint with food coloring.
• 5

  Assemble cake starting with the 8-inch layers. Spread a bit of jam and a little of the white buttercream on each layer. Stack the 6-inch layers and the layers from the can on top, repeating the jam and buttercream. Place cupcake on top and coat the entire cake with a thin layer of buttercream, smoothing the sides to create uniform edges. Chill until cold, 20 to 30 minutes.
• 6

  Transfer cake to a serving platter to decorate. Place colored buttercream in piping bags fitted with a coupler and a #12 plain tip (we bought multiple tips but you can also wash one between colors). Starting at the base with purples and blues, pipe dots around the entire cake in rows. Finish with reds and pink on top.
• 7

  Keep cake chilled until ready to serve. When buttercream is cold, cake can be loosely wrapped in plastic and will keep, chilled, for up to two days.
• 8

  BUTTERCREAM: To make the meringue buttercream, cut 4 cups unsalted butter into small pieces and bring to room temperature. Whisk together 10 egg whites and 2 1/2 cups sugar in a heat-proof mixing bowl over a pan of simmering water until sugar has dissolved, about 5 min. Test by rubbing the warm mixture between your fingers -- you shouldn't feel any sugar crystals.
• 9

  Transfer bowl to the mixer stand and whisk on high speed until cool and stiff peaks form, 10 to 12 minutes.
• 10

  Reduce speed to medium high and add butter a little at a time. (Buttercream may curdle but will become smooth as you continue to beat it.) Add 2 teaspoons vanilla extract.
• 11

  Use within a few hours or refrigerate for up to a week. Before using, bring to room temperature, and beat on low until smooth.
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