Step 1

Heat oven to 350°F. Grease bottom of 13x9-inch pan with shortening or cooking spray. Make brownie batter as directed on box for cakelike brownies. Stir in zucchini and chocolate chips. Spread in pan.

Step 2

Bake 22 to 26 minutes or until toothpick inserted 2 inches from side of pan comes out almost clean. Cool completely on cooling rack, about 1 hour.

Step 3

Spread frosting over top. Store covered in refrigerator.