1 cup (2 sticks) butter or margarine, softened
1 cup crunchy peanut butter
1 box (1 pound) powdered sugar
1 1/2 cups graham cracker crumbs
1 package (6 oz.) semisweet or milk chocolate chips

Blend butter and peanut butter in a large bowl. Work in powdered sugar and graham cracker crumbs with a wooden spoon until thoroughly combined. Press mixture evenly into a 13x9x2-inch backing pan. Melt chocolate pieces in top of a double boiler over hot water (or in microwave) Quickly spread over top of cookies. Place in refrigerator and chill until firm. Cut into small squares.