Blackberry Buttermilk Cake - cooking recipe

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

Preparation

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. 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. 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. 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.