1Heat oven to 350°F (325°F for dark or nonstick pan). Grease bottom only of 9-inch square pan with shortening or cooking spray. In small bowl, beat all filling ingredients with electric mixer on low speed until smooth. Set aside.
2Make brownie batter as directed on box, using 1/4 cup oil, 2 tablespoons water and the egg. Spread 3/4 of the batter in pan. Spoon filling by tablespoonfuls evenly over batter. Spoon remaining brownie batter over filling. Cut through batter several times with knife for marbled design.
3Bake 40 to 45 minutes or until toothpick inserted 1 inch from side of pan comes out almost clean. Cool completely. Cut into 4 rows by 4 rows. Store covered in refrigerator.