Inspired by a cake popular in the '70s, I developed this recipe for a larger, more flavorful, slightly less sweet cake. It yields 32 servings and can be made start-to-finish, including frosting, in under an hour. The only special equipment required is a Sheet Pan Half Size - 12-7/8'' x 17-3/4'' Heavy Duty, 13 Gauge, the same one I use for my Meyer lemon sheet cake and so many other things. I hope you'll try it and let me know what you think.
Chocolate Buttermilk Sheet Cake(Makes 18x13x1-inch half-sheet, 32 servings)
1 1/4 cups water or cold coffee
1 1/4 cups (2 1/2 sticks) unsalted butter
1/2 cup natural unsweetened cocoa
1 1/2 teaspoons instant espresso powder
2 1/2 dip-and-sweep cups (12.5 ounces) unbleached all-purpose flour
2 cups sugar
1 1/2 teaspoons baking soda
3/4 teaspoon salt
3/4 cup buttermilk
3 large eggs, lightly beaten
1 1/2 teaspoons vanilla extract
1/2 cup (1 stick) unsalted butter
1/3 cup buttermilk
1/4 cup natural unsweetened cocoa
1 teaspoon vanilla extract
1/2 teaspoon espresso powder
1/8 teaspoon salt
3 cups confectioner’s sugar
1 1/2 cups (6 ounces) finely chopped pecans, toasted
1 Preheat oven to 350. Spray an 18x13x1-inch half-sheet pan with cooking spray; don’t try to make-do with a smaller pan, or the batter will overflow.
2 In 2-quart saucepan, combine water, butter, cocoa and espresso powder. Heat, whisking occasionally, over medium heat until the butter melts.
3 In large mixing bowl, whisk together flour, sugar, baking soda and salt. Whisking for about 30 seconds sort of sifts the dry ingredients. In 2-cup glass measure, combine buttermilk, eggs and vanilla. Add warm liquid mixture to dry ingredients and stir to combine; beat for about 30 seconds. Add the buttermilk mixture and beat for another 30 seconds. (A wooden spoon works perfectly well, but I use an English cake whisk, a kind of stainless steel wire spoon that has been made in Britain for over a hundred years.)
4 Pour into prepared pan. Bake at 350 for about 25 minutes, or until toothpick inserted in center comes out clean. Cool slightly (10 minutes) on wire rack while making the frosting. The slight cooling before pouring on the frosting gives the cake a better texture.
5 In same 2-quart saucepan (no need to wash it) over low heat, combine butter, buttermilk, cocoa, vanilla, espresso powder and salt. When butter is melted, bring to a boil; remove from heat. Whisk in confectioner’s sugar, whisking vigorously until smooth. Stir in toasted pecans. After cake has cooled for 10 minutes, pour warm frosting over warm cake and spread quickly. Cool in pan on wire rack for at least 4 hours.