- 1/2 cup butter or margarine, softened
- 1 1/4 cups packed brown sugar
- 1 egg
- 1 teaspoon vanilla extract
- 3/4 cup water
- 1/2 cup milk
- 1 1/2 cups all-purpose flour
- 6 tablespoons baking cocoa
- 1 1/2 teaspoons cream of tartar
- 1 teaspoon baking soda
- 1 teaspoon baking powder
- 1/4 teaspoon salt
- FROSTING:
- 1/2 cup butter or margarine, softened
- 1 cup confectioners' sugar
- 1/4 cup baking cocoa
- 1 tablespoon milk
- 1 (16 ounce) can vanilla frosting
- Grease a 13-in. x 9-in. x 2-in. baking pan; line with parchment paper. Grease the paper; set aside. In a mixing bowl, cream butter and brown sugar. Beat in egg and vanilla. Combine water and milk. Combine the flour, cocoa, cream of tartar, baking soda, baking powder and salt; add to creamed mixture alternately with milk mixture.
- Pour into prepared pan. Bake at 350 degrees F for 22-27 minutes or until a toothpick inserted near the center comes out clean. Cool for 10 minutes before inverting onto a wire rack. Remove and discard parchment paper. Cool cake completely.
- For frosting, in a mixing bowl, cream butter, confectioners' sugar and cocoa until smooth. Beat in enough milk to achieve spreading consistency. Transfer cake to a serving platter or covered board. Spread with chocolate frosting; decorate with vanilla frosting.