2 1/4 cups sifted all-purpose flour
1 1/4 teaspoons baking soda
1/4 teaspoon salt
1/2 cup sifted natural cocoa, such as Hershey's regular
8 tablespoons (1 stick) unsalted butter, at room temperature
1 1/2 cups granulated sugar
1 teaspoon vanilla extract
2 large eggs, at room temperature
1 1/2 cups buttermilk
6 cups sifted confectioners' sugar, or more as needed
1/3 cup sifted unsweetened natural cocoa, such as Hershey's regular
5 to 6 tablespoons extra-strength coffee or espresso (or 1 tablespoon instant coffee powder dissolved in 1/2 cup hot water)
Special Equipment: Two 8 by 1 1/2-inch round cake pans or 9- to 9 1/2-inch (6 1/2 to 8-cup) tube or Bundt pan; baking parchment, wax paper, or foil; 1 or 2 foil-covered 8- or 9- or 10-inch cardboard cake disks or flat plates; wooden skewer or cake tester.
Pan Preparation: Generously coat the pan(s) with solid shortening, line with baking parchment or wax paper (for a tube or Bundt pan, cut a paper or foil ring), grease the liner, and dust with sifted cocoa; tap out the excess cocoa.