Chocolate Sheet Cake

From the kitchen of the Davis Family in Dallas, Texas

2 cups flour
2 cups sugar
1 stick margarine
1/2 cup Crisco or cooking oil
1 cup water
3 tablespoons cocoa
2 eggs
1/2 cup buttermilk
1 teaspoon soda
1 teaspoon vanilla
ICING:
1 stick margarine
3 tablespoons cocoa
4 tablespoons milk
1 box powdered sugar
1 teaspoon vanilla
1/2 cup chopped nuts (optional)

In large bowl, sift together flour and sugar. Bring to a boil the following: margarine, Crisco or cooking oil, water, and cocoa. Whip into flour and sugar. Mix together eggs, buttermilk, soda and vanilla and then add to mixture. Batter will be thin. Bake in a large sheet pan or 2 small sheet pans at 350 degrees about 25 minutes or until done. Icing: Bring to a boil: margarine, cocoa, milk, powdered sugar and vanilla. Mix while hot. Pour on warm cake. 1/2 cup chopped nuts may be added to icing.