1Heat oven to 350ºF (325ºF for dark or nonstick pan). Grease bottom only of 8-inch or 9-inch square pan with cooking spray or shortening. (For easier cutting, line pan with foil, then grease foil on bottom only of pan.) Make brownies as directed on box. Cool completely.
2Stir cream cheese, powdered sugar, orange juice, 2 drops yellow food color and 1 drop red food color until smooth and spreadable; spread over brownies.
3Place chocolate chips and shortening in small microwavable bowl. Microwave uncovered on Medium (50%) about 2 minutes or until mixture can be stirred smooth. Drizzle over brownies. Refrigerate about 30 minutes or until cream cheese and chocolate are set.
4For 24 brownies, cut into 4 rows by 6 rows. Cover and refrigerate any remaining brownies.