Mix flour and sugar together in a large bowl.
In a medium saucepan over medium heat bring the water, butter (1 stick), shortening, buttermilk and cocoa to a light boil and then pour over the flour mixture and stir until blended.
Gradually add the eggs, vanilla, food coloring and soda; mix well.
Pour into a lightly greased 11x17 inch pan.
Bake at 350 degrees for 20-25 minutes or until a toothpick inserted in the middle comes out clean.
To make the icing blend together butter (1 stick), cream cheese and vanilla.
Add the powdered sugar gradually and blend until light and fluffy.
Spread over warm cake.