Texas Sheetcake

I made this last weekend and remembered how fast, easy, and yummy it is! I found this recipe on realmomkitchen.blogspot.com. I've halved the amount of cinnamon here.

2 sticks butter or margarine
1 cup water
4 heaping tablespoons unsweetened cocoa powder
2 cups all-purpose flour
2 cups white sugar
2 eggs
1/2 teaspoon cinnamon
1/2 cup buttermilk
1 teaspoon baking soda
1 teaspoon vanilla

Grease a 15x10 inch jelly roll pan. Bring 2 sticks butter, water and 4 tablespoons cocoa to a boil in a large saucepan. While still hot, remove from heat and add to 2 cups flour and 2 cups white sugar. Mix well. Add in eggs, cinnamon, buttermilk, baking soda, and vanilla. Do not mix too long.
Pour batter into greased 15x10 inch jelly roll pan. Bake at 400 degrees for 20 minutes, or until a toothpick inserted into center of cake comes out clean.

Icing
1/2 cup butter
4 heaping tablespoons unsweetened cocoa powder
3 tablespoons milk
3 tablespoons water
3 1/2 cups confectioners' sugar
1 teaspoon vanilla extract
1 cup chopped walnuts or pecans (if desired)

Bring 1/2 cup butter or margarine, 4 tablespoons cocoa, 3 tablespoons water, and 3 tablespoons milk to a boil. Remove from heat. While still hot, add confectioners' sugar, vanilla, and nuts. Beat well. Ice cake while icing is still hot.