Preheat oven to 350 degrees. Line 8-9 inch square pan with foil, leaving 1 inch of foil overhanging at 2 opposite sides of pan. Spray foil with cooking spray. Make and bake brownies as directed on box, using water, oil and egg. Cool completely in pan on cooling rack; about 1hour.
Freeze uncut brownies 30 minutes. Use foil to lift out of pan. Cut into 5 rows by 3 rows. Roll each brownie into a ball. Roll balls in chocolate sprinkles, pressing to adhere.
In a small microwavable bowl, microwave candy coating on medium 30 seconds, then in 15 second increments until melted; stir until smooth. Dip tips of wafer cookies in melted candy; insert into truffles to look like wings. Use remaning melted candy to attach 2 green chocolate candies to each truffle for the eyes.