Recipe for RAINBOW CAKE WITH WHITE CHOCOLATE BUTTERCREAM

RAINBOW CAKE WITH WHITE CHOCOLATE BUTTERCREAM
Desserts
Contributed by: Michelle Meyer
Ingredients: For the cake: 1 cup whole milk, at room temperature 6 large egg whites, at room temperature 2 tsp. almond extract 1 tsp. vanilla extract 21?4 cups cake flour 13?4 cup granulated sugar 4 tsp. baking powder 1 tsp. table salt 12 TBS unsalted butter, softened Red, orange, yellow, green, blue and purple gel food coloring For the frosting: 21?2 cups granulated sugar 10 large egg whites 2 lbs. unsalted butter, softened and cut into tablespoons 2 tsp. pure vanilla extract 1 lb. white chocolate, melted and cooled
Preheat oven to 350 degrees. Butter six 7- or- 8-inch cake pans (or three, to bake in two batches) and line the bottom with parchment paper rounds. Butter the rounds and set the pans aside. Pour the milk, egg whites and extracts into a 2-cup glass measuring cup and mix with fork until blended. Mix the flour, sugar, baking powder and salt in bowl of an electric mixer at a low speed. Add the butter and continue beating on low speed until mixture resembles moist crumbs, with no powdery streaks remaining. Add all but 1?2 cup of milk mixture and beat at medium speed for 11?2 minutes. Add remaining 1?2 cup milk mixture and beat 30 seconds more. Stop and scrape the sides of the bowl. Beat at medium or high speed for 20 seconds. Divide batter evenly among six medium bowls. Add enough of each color of food coloring to each bowl, whisking until desired shade is reached. Transfer each color to an individual cake pan and bake for 15 to 25 minutes or until a toothpick inserted in the middle of each cake comes out clean. Let cakes rest in pans for three minutes. Loosen from sides of pans with a knife and invert onto wire racks. Allow to cool completely. At this point, layers may be wrapped in plastic wrap and frozen for later use. To make the frosting, put sugar and egg whites in the heatproof bowl of an electric mixer and set over a pan of simmering water. Whisk constantly until sugar is dissolved and mixture registers 140 degrees on an instant-read thermometer. Transfer bowl to an electric mixer fitted with the whisk attachment; beat on medium-high speed until fluffy and cooled, about 10 minutes. Continue beating until stiff peaks form. Reduce speed to medium-low; add butter by the tablespoon, beating well after each addition. Beat in vanilla and white chocolate. Assemble cake, frosting between layers and top and sides of cake. (Cake recipe from Cooks Illustrated; icing recipe from Martha Stewart.)
(This recipe was contributed as part of a "Cook of the Week" feature.)