Mix in heavy sauce pan 1/2 cup butter and cocoa powder; stir until butter is melted. Remove from heat; stir in 1/2 cup powdered sugar, the egg, and vanilla. Add Graham cracker crumbs. Stir until combined. Press into bottom of an ungreased 13x9x2 inch pan. Chill 1 hour. Melt 1/2 cup butter in mixing bowl. Add creme de menthe, gradually add 3 cups powdered sugar; beat until smooth. Spread over chocolate layer. Chill 1 hour. Combine 1/4 cup butter and chocolate pieces. Heat until chocolate is melted. Spread over mint layer. Chill until firm. Cut into squares.{$7e}(Original recipe for 12)
