PREHEAT oven to 375°F. Combine flour, oats, baking soda, baking powder and salt; set aside. Beat margarine, peanut butter, brown sugar and granulated sweetener in large bowl with electric mixer on medium speed until light and fluffy. Add egg and vanilla; mix well. Gradually add flour mixture, mixing after each addition until well blended. Stir in chopped chocolate.
DROP heaping tablespoonfuls of dough, 2 inches apart, onto ungreased baking sheets; flatten slightly.
BAKE 10 to 11 min. or until lightly browned. Cool on baking sheet 1 min.; remove to wire racks. Cool completely.