Heat oven to 350°F. Spray or grease bottom only of 13x9-inch pan. Make brownie batter as directed on box--except stir in peanuts. Spread in pan.
Bake 24 to 26 minutes or until toothpick inserted 2 inches from side of pan comes out almost clean. Immediately sprinkle warm brownies with marshmallows and chocolate chips.
Bake about 3 minutes longer or until marshmallows are puffed. Cool 30 minutes.
In small microwavable bowl, microwave frosting uncovered on High 15 seconds; stir in food color. Drizzle over bars. Cool completely, about 1 hour. Cut into 6 rows by 4 rows. Top each bar with 1 candy.