DIRECTIONS
In a large mixing bowl, cream butter and sugar until light and fluffy. Add eggs, one at a time, beating well after each addition. Beat in vanilla. Combine the flour, baking soda and salt; add to creamed mixture alternately with buttermilk, beating well after each addition. Stir in chocolate until combined.
Pour into a greased 15-in. x 10-in. x 1-in. baking pan. Bake at 350° for 23-27 minutes or until a toothpick inserted near the center comes out clean. Cool on a wire rack.
For frosting, in a small saucepan, bring cocoa and milk to a boil over medium heat, stirring constantly. Remove from the heat; stir in butter and vanilla until butter is melted. Whisk in confectioners' sugar until smooth. Drizzle over cake and spread quickly. Let stand until set. Yield: 12 servings.