Blackberry Buttermilk Cake

from Martha Stewart Weddings

• Ready In: 40 mins
• Serves: 70
• Yields: 2 cakes

Ingredients

• for the buttermilk cake

•  vegetable oil cooking spray
• 8  cups all-purpose flour, plus more for tossing berries
• 3  tablespoons baking powder
• 1 1⁄2 teaspoons salt
• 3⁄4 teaspoon baking soda
• 3  cups unsalted butter, softened
• 5 1⁄4 cups sugar
• 2  tablespoons pure vanilla extract
• 12  large eggs
• 1 1⁄2 cups buttermilk
• 150  fresh blackberries (about 6 cups)

• for the frosting

• 6  large eggs, separated
• 1 1⁄2 cups sugar
• 2  cups  whole milk
• 1  teaspoon pure vanilla extract
• 6  cups unsalted butter, softened
• 1⁄2 cup  blackberry  puree (about 3 cups whole berries)
• 7  lbs  rolled  fondant

Directions

1. 1. Preheat oven to 350 degrees. Coat cake pans with cooking spray; cover bottoms with parchment, and coat again; set aside. Sift together flour, baking powder, salt, and baking soda in a large bowl; set aside.
2. 2. Put butter and sugar into the bowl of an electric mixer fitted with the paddle attachment; mix on medium speed until fluffy, about 12 minutes. Mix in vanilla. Add eggs, 1 at a time, mixing well after each addition. Add flour mixture in 2 batches, alternating with the buttermilk. Divide batter among prepared pans. Gently toss berries in flour to coat completely, and gently press into batter.
3. 3. Bake until a cake tester inserted in centers comes out clean. (If the cakes become too dark while baking, cover with foil.) Transfer to wire racks; let cool in pans slightly. Invert cakes onto racks. Remove parchment, and reinvert. Cakes can be wrapped in plastic and stored up to 1 day.
4. 4. To assemble: Review Cake Assembly instructions. Cut each cake in half horizontally, making 4 layers of each size. Spread buttercream on 3 cake layers (see note below for amounts). Stack layers, placing the plain layer on top. Coat tiers with buttercream; chill. Smooth fondant over tiers.