Preheat oven to 325. Prepare a 13"x9" pan with cooking spray; set aside. In a mixing bowl, combine brownie mix, water, egg, and oil. Mix until all is moistened. Bake for 30 minutes, or until toothpick inserted in center comes out clean. Meanwhile, prepare pudding mix according to package directions; set aside. In a mixing bowl, combine powdered sugar and cream cheese. Mix for one minute or until until smooth; set aside. Sprinkle cooled, baked brownies with 1 1/2 cups chocolate chips. Spread cream cheese mixture evenly overtop. Spread chocolate pudding mixture evenly over cream cheese mixture. Spread whipped topping evenly over all in pan. Sprinkle remaining half cup chips over top. Refrigerate several hours before serving.