Grease bottom only of square baking dish, 8 x 8 x 2-inches. Mix brown sugar, margarine, egg, and vanilla. Stir in flour, oats, baking powder, and salt. Spread evenly in baking dish. Sprinkle with chocolate chips and nuts. Microwave uncovered on high (100%), 4 minutes; turn dish one-quarter turn. Microwave until no longer doughy, 2 to 3 minutes. Cool; cut into about 2 inch squares. Makes 16 Cookies