In a large glass bowl in the micro, or in a pot if no micro, melt together 1 pound butter and 1 pound Velveeta cheese. (Yes, that's right.) When melted and still hot, beat in 1 1/2 c. dry cocoa, then quick, before it cools, beat in 4 pounds (yes, four) powdered sugar. You may have to use a wooden spoon to finish getting all the sugar in. Add chopped nuts if you wish, spread into buttered pan, chill and cut into squares. You won't believe how good it is.