Instructions

• Preheat oven to 375°F. Grease and flour a 9×13-inch cake pan.
• In a large bowl, whisk together the dry ingredients: 2 cups white sugar, 2½ cups flour, 4 tablespoons cocoa powder, 1½ teaspoons baking soda, 1½ teaspoons baking powder, and 1 teaspoon salt.
• Add the wet ingredients to the dry mixture: 2 eggs (room temperature), 1 cup buttermilk, 2 teaspoons vanilla, 1 cup hot coffee, and 1 cup vegetable oil.
• Beat the batter on medium speed for about 2 minutes. The batter will be thin.
• Pour the batter evenly into the prepared 9×13-inch pan.
• Bake for 30–40 minutes, or until a cake tester or toothpick inserted in the center comes out clean.
• Remove the cake from the oven and let it cool in the pan for 10 minutes.
• While the cake is cooling, make the frosting: in a medium saucepan over medium-low heat, melt ½ cup butter.
• Remove the pan from heat and whisk in ½ cup cocoa powder until smooth.
• Return the saucepan to medium-low heat and heat just until the mixture begins to boil; then remove from heat immediately.
• Off the heat, whisk in 3 cups powdered sugar (sift first if desired to remove lumps). Then add ½ tablespoon vanilla and 2 tablespoons coffee and stir until smooth.
• Let the frosting cool for about 10 minutes to thicken slightly so it spreads more easily. Do not let it cool so long that it hardens.
• Spread the frosting over the cake while the cake is still in the pan (after the initial 10-minute cooling) and the frosting is at a spreadable consistency.