Put water, butter and cocoa ... in greased cookie sheet. Bake 15 minutes at ... 5 minutes before cake is done. Heat everything except ... milk to make buttermilk.
Preheat oven to 375 degrees. Spray 16" x 12 3/4" sheet pan; set aside. Beat batter, ... from pan. Remove cake from pan after 5 minutes, ... rack. Makes 12 servings.