Melt the cheese and butter together in a double boiler or over low heat. Stir often to keep from scorching. Sift the cocoa and powdered sugar -- NO LUMPS. Mix sugar-cocoa mixture into the melted mixture and blend thoroughly (use hands). Add nuts and vanilla; blend again. Press ito (2) 9" x 13" pans. Yields 7 pounds. Cut into very small pieces, VERY RICH! Freezes very well.