1Heat oven to 350°F (325°F for dark or nonstick pan). Grease bottom only of 13x9-inch pan with shortening or cooking spray. (For easier cutting, line pan with foil, then grease bottom only of foil.) Make brownie mix as directed on box for 13x9-inch pan. Cool completely, about 1 1/2 hours.
2In large bowl, beat softened butter and cream cheese with electric mixer on medium speed until smooth. Add 1/4 cup whipping cream; beat until blended. Slowly add powdered sugar; beat until fluffy. Add mint extract and food color; blend well. Spread over cooled brownies. Refrigerate about 1 hour or until set.
3Meanwhile, in nonstick 2-quart saucepan, heat Topping ingredients over medium-low heat, stirring constantly, until melted and smooth. Cool about 10 minutes or until lukewarm.
4Pour topping over filling; spread to cover. Refrigerate uncovered about 2 hours or until set. Before cutting, let stand 20 minutes at room temperature. For brownies, cut into 9 rows by 4 rows. Store covered in refrigerator.