1 cup milk ½ cup vegetable oil 2 teaspoons vanilla extract 1 cup boiling water
Frosting: ¾ cup unsalted butter, at room temperature 5 ⅓ cups confectioners' sugar 1 ½ cups unsweetened cocoa powder ⅔ cup milk 1 teaspoon vanilla extract
Directions Start with a 350°F oven. Grease and flour two 9-inch circular pans. Make cake: Mix sugar, flour, cocoa, baking soda, baking powder, and salt in a bowl.
Mix eggs, milk, oil, and vanilla for 3 minutes with an electric mixer. Stir boiling water by hand.
Bake for 30–35 minutes in the preheated oven until a toothpick inserted into the centers comes out clean. Cool 10 minutes before removing from pans to finish cooling.
Make frosting as cakes cool: Mix butter with an electric mixer until frothy. Mix confectioners' sugar, cocoa, milk, and vanilla. Beat to spreadable consistency.
Divide the chilled cake horizontally, frost the tops, and place them on a serving platter. Frost cake outside with leftover icing.