Microwave 12 ounce package semi-sweet chocolate pieces and 1 cup chunky peanut butter in a 2 quart bowl on medium (50%) 2-3 minutes or until chocolate is melted, stirring after each minute. Fold in 4 cups miniature marshmallows. May use nuts, also, if desired. Spread into greased (buttered) 9 inch square pan. Chill until firm. Cut into squares. Makes 2 dozen.