1Line 8-inch square pan with foil, leaving foil overhanging at 2 opposite sides of pan; spray foil with cooking spray.
2In large microwavable bowl, microwave chocolate chips uncovered on High 1 minute. Spoon frosting over chips. Microwave on High 30 seconds; stir. If necessary, continue to microwave in 15-second increments until mixture can be stirred smooth. Spread in pan. Refrigerate 30 minutes or until set.
3Use foil to lift fudge out of pan. Cut into 8 rows by 8 rows.