1. Heat oven to 350ºF (325ºF for dark or nonstick pan). Grease bottom only of 9-inch square pan with shortening or cooking spray. In small bowl, beat filling ingredients with electric mixer on low speed until smooth. Set aside.
2. Make brownie batter as directed on box. Spread 3/4 of brownie batter in pan. Spoon filling by tablespoonfuls evenly onto brownie batter. Spoon remaining brownie batter over filling. Cut through mixture with knife several times for marbled design. Sprinkle with chocolate chips.
3. Bake 40 to 44 minutes or until toothpick inserted in brownie 1 inch from side of pan comes out almost clean. Cool completely, about 1 1/2 hours. For 16 brownies, cut into 4 rows by 4 rows. Store covered in refrigerator.