Texas Sheet Cake

2 cups all-purpose flour

2 cups white sugar

1 cup butter

1 cup water

1/2 cup shortening

1/2 cup unsweetened cocoa powder

1/2 cup buttermilk

2 eggs

1 teaspoon baking soda

1 1/2 teaspoons vanilla extract

6 tablespoons milk

4 cups confectioners' sugar

Directions

1. Sift together and set aside in large bowl the flour and sugar.
2. In saucepan over medium heat bring to a boil; 1/2 cup margarine or butter, 1/2 cup shortening, 1 cup water, and 4 tablespoons cocoa.
3. Pour cocoa mixture over flour and sugar mixture. Stir in buttermilk, eggs, baking soda, and 1/2 teaspoon vanilla. Mix well and pour into a greased and floured sheet pan.
4. Bake in a preheated 350 degrees F (205 degrees C) oven for 20 minutes.
5. To Make Frosting: Five minutes before cake is done, bring to boil in a saucepan 1/2 cup margarine or butter, 6 tablespoons milk, and 4 tablespoons cocoa. Remove from heat and immediately stir in the confectioners' sugar, nuts (if desired), and 1/2 teaspoon vanilla extract. Beat until smooth and immediately pour frosting over cake. Cake may be served warm or at room temperature.