Rainbow Cake

I promised my friend Rula I would post more. We have a blog pact which I have been neglecting but I know she will both appreciate this cake and the sentiment behind it! This rainbow cake is in celebration of Ref 74 passing in Washington. I am super happy to live in a state where gay men and women have the same rights as everyone else, to marry the person that they love. In Washington, the additional revenue from marriage licenses for same-sex marriage (conservatively estimated at $50,000) will be going to help at risk LGBT youth. We also legalized marijuana but just to be clear, this cake isn't "special". Just beautiful and delicious.

The cake turned out great. Not only did the various layers look vibrant, but it was also really delicious (coming from someone who is usually not a fan of white cake). I made this whipped frosting which was tasty but did not hold up overnight. I'm including the original frosting recipe but if you'll be eating it right away, this whipped frosting is super light and tasty (I'm also not a fan of buttercream).

Rainbow Cake

CAKE
Vegetable shortening
3 cups all-purpose flour
4 teaspoons baking powder
1/2 teaspoon salt
2 sticks (1 cup) unsalted butter, room temperature
2 1/3 cups sugar
5 large egg whites, room temperature
2 teaspoons pure vanilla extract
1 1/2 cups milk, room temperature
Red, orange, yellow, green, blue, and purple gel food coloring
FILLING AND CRUMB COAT
9 large egg whites
1 3/4 cups sugar
2 cups (4 sticks) unsalted butter, cut into small pieces, room temperature
2 teaspoons pure lemon extract
FROSTING
5 large egg whites
1 cup sugar
1 cup (2 sticks) unsalted butter, cut into small pieces, room temperature
1 teaspoon pure lemon extract
1. For the cake: Preheat oven to 350 degrees. Brush six 9-inch-round cake pans (or as many 9-inch cake pans as you have, reusing them as necessary) with shortening. Line bottom of each cake pan with parchment paper; brush again and set aside.
2. In a large bowl, whisk together flour, baking powder and salt; set aside. In the bowl of an electric mixer fitted with the paddle attachment, cream together butter and sugar. Slowly add egg whites and mix until well combined. Add vanilla and mix until fully incorporated. Add flour mixture and milk in two alternating additions, beginning with the flour and ending with the milk. Mix until well combined.
3. Divide batter evenly between 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. Transfer to oven and bake until a cake tester inserted into the center of each cake comes out clean, about 15 minutes (working in batches if necessary).
4. Remove cakes from oven and transfer to a wire rack; let cool for 10 minutes. Invert cakes onto a wire rack; re-invert and let cool completely.
5. For the filling and crumb coat: Cook egg whites and sugar in a small saucepan over medium heat, whisking constantly until sugar is completely dissolved. Transfer to the bowl of an electric mixer fitted with the whisk attachment; mix on high speed until mixture is room temperature. With the mixer on medium-low, add butter, one piece at a time, mixing well after each addition. 6. Remove whisk attachment and switch to paddle attachment. Increase speed to high and beat until buttercream comes together, about 5 minutes; beat in lemon extract. 7. For the frosting: In a clean saucepan and bowl of an electric mixer, repeat process in step 1. 8. Using a serrated knife, trim tops of cakes to make level. Place four strips of parchment paper around perimeter of a serving plate or lazy Susan. Place the purple layer on the cake plate. Spread a scant 1 cup buttercream filling over the first layer with a small offset spatula so it extends just beyond edges. Repeat process with blue, green, yellow, and orange layers.
9. Place the remaining red layer on top, bottom-side up. Gently sweep away any loose crumbs with a pastry brush. Using an offset spatula, cover the top and sides with a thin layer of frosting (also use any of the excess frosting visible between the layers). Refrigerate until set, about 30 minutes.
10. Using an offset spatula, cover cake again with remaining frosting.

From Martha Stewart
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