Preheat oven to 350 degrees. Pat rolls into an ungreased 10-by-15-inch jelly roll pan. Gently press dough to cover bottom of pan, being sure to seal perforations. In a small saucepan, combine Brown Sugar Twin and margarine. Boil 1 minute. Pour mixture evenly over dough. Sprinkle with walnuts. Bake 12 to 16 minutes or until golden brown. Remove from oven and immediately sprinkle with chocolate chips. Slightly swirl pieces as they melt, leaving some pieces partially whole to create an uneven appearance. Cool on wire rack. Cut into 32 bars. HINT: Do not use inexpensive crescent rolls. They will not cover the pan properly.