Put in saucepan and bring to a boil.

1 stick butter
1/2 c. cooking oil
4 tbsp. cocoa
1 c. water

Sift together:

2 c. sifted flour
2 c. sugar

Pour chocolate sauce over dry ingredients and mix well. Then add:

1/2 c. buttermilk
2 eggs
1 tsp. baking soda
1 tsp. vanilla

Pour batter into greased broiler pan or large jelly roll pan (11 x 17). Bake at 400 degrees for 20 minutes. While sheet cake is hot, frost with frosting.

FROSTING:

1 stick butter
4 tbsp. cocoa
1/3 c. buttermilk
1 lb. confectioners' sugar
1/2 tsp. salt
1 tsp. vanilla
1 c. chopped nuts

Bring butter, cocoa, buttermilk to boiling point. Remove from heat, add rest of ingredients. Frost. When cool, cut into squares; remove from pan. Makes 30 large square.