Combine 2 cups sugar and 2 cups all purpose flour. Bring 1 cup butter, 4 tablespoons cocoa and 1 cup water to boil; pour over sugar and flour. Mix slowly. Add 2 slightly beaten eggs. Add 1/2 cup buttermilk 1 teaspoon baking soda and 1 teaspoon vanilla. Pour into greased 11 x 16 inch pan. Bake at 375 degrees for 25 minutes.

FUDGE ICING: In saucepan, combine 1/2 cup butter, 4 tablespoons cocoa and 6 tablespoons milk; bring to boil, stirring constantly. Remove from heat. Add 1 pound confectioners' sugar, 1 teaspoon vanilla and 1 cup chopped nuts (optional). Spread hot icing over hot cake.