The cake layers can be wrapped well in plastic and refrigerated for up to 2 days; trim the tops just before assembling.

　　

Ingredients

Makes one 9-inch layer cake

　　Unsalted butter, for the pans

　　4 1/4 cups all-purpose flour, plus more for dusting

　　3 1/3 cups sugar

　　3 1/2 teaspoons baking soda

　　1 3/4 teaspoons baking powder

　　1 3/4 teaspoons salt

　　3 large eggs plus 1 large yolk

　　1 3/4 cups warm water

　　2 cups buttermilk

　　3/4 cup vegetable oil

　　2 teaspoons pure vanilla extract

　　Vanilla or Chocolate Buttercream Frosting (recipes opposite and preceding recipe)

　　

Step 1

Preheat the oven to 350°F, with racks in the upper and lower thirds. Cut 2 9-inch rounds of parchment paper to line the bottoms of 2 9-inch (2 inches deep) round cake pans. Butter and line the pans. Butter the linings. Dust the pans with flour, tapping out excess. Set aside.

　　

Step 2

Sift together the flour, sugar, baking soda, baking powder, and salt into the bowl of an electric mixer. Return the bowl to the mixer; fit the mixer with the paddle attachment. Add the eggs, yolk, warm water, buttermilk, oil, and vanilla. Mix on low speed until the mixture is smooth, about 3 minutes.

　　

Step 3

Divide the batter evenly between the prepared pans. Bake, switching the positions of the pans and rotating them halfway through, until a cake tester inserted into the centers comes out clean, about 42 minutes. Let cool in the pans on wire racks 30 minutes. Run a thin knife around the edges of the cakes to loosen. Unmold; peel off the parchment. Let cool completely, top sides up, on the racks.

　　

Step 4

Trim the tops of the cake layers with a long serrated knife to make them level. Using a small offset spatula, evenly cover the top of one cake layer with 1 1/2 cups frosting; spread the frosting so it extends just beyond the edges of the cake.

　　

Step 5

Place the second cake layer, cut side down, on top; press gently to make it level. Frost the top and sides of assembled cake with the remaining frosting.

　　Reprinted with permission from The Martha Stewart Living Cookbook: The New Classics by Martha Stewart Living Magazine, copyright © 2007. Published by Clarkson Potter, a division of The Crown Publishing Group.Buy the full book from Amazon.