Cake ▢2 cups all-purpose flour ▢2 cups sugar ▢½ cup unsweetened cocoa powder ▢1 tablespoon baking soda ▢1 teaspoon salt ▢2 eggs ▢1 cup buttermilk ▢1 cup hot water ▢⅔ cup vegetable oil Frosting ▢½ cup unsalted butter ▢2 tablespoons unsweetened cocoa powder ▢5 tablespoons milk ▢1 teaspoon vanilla extract ▢3½ cups powdered sugar, sifted ▢sprinkles, for topping (optional)
Preheat the oven to 350°F. Mix 2 cups flour, 2 cups sugar, ½ cup cocoa powder, 1 tablespoon baking soda, and 1 teaspoon salt in a large bowl.
Add 2 eggs, 1 cup buttermilk, 1 cup hot water, and ⅔ cup oil. Beat with a hand mixer until combined and smooth (it should be runny). Pour into a greased 11x15-inch baking dish.
Bake for 20 minutes, or until a toothpick inserted in the middle comes out clean.
Melt ½ cup butter in a medium pot over low heat. Add 2 tablespoons cocoa powder, 5 tablespoons milk, and 1 teaspoon vanilla and whisk until smooth.
Add 3½ cups powdered sugar and whisk until smooth. Remove from the heat and pour over the warm cake. Spread frosting quickly and add sprinkles right away, since frosting sets up quickly.