Optional - lemon slices and fresh herbs for serving.
Preheat the broiler to 525 degrees and prepare a broiler pan or baking sheet by lining with aluminum foil and using a light coating of cooking spray.
In a small bowl, use a spoon to mix together the Parmesan cheese, butter, mayonnaise and lemon juice. Season with dried parsley, pepper, onion powder and salt. Mix well and set aside.
Arrange fillets in a single layer on the prepared pan. Broil a few inches from the heat for 2 to 3 minutes. Flip the fillets over and broil 2 more minutes.
Remove the fillets from the oven and spread with the Parmesan cheese mixture on the top side. Broil for 2 more minutes or until the topping is browned and fish flakes easily with a fork. Internal temp should read 145 degrees F.
Serve with lemon slices and chopped herbs if desired.
Storage: Store leftovers in an airtight container in the fridge for up to 3 days.Freezing: Freeze broiled tilapia filets in a single layer on a baking sheet. Once solid, transfer to a freezer safe container or bag, removing as much air as possible. Thaw and reheat within 3 weeks.Reheating: If frozen, thaw fish first before reheating. Preheat your oven to 350 and heat the fish for 5-10 minutes or until warmed through.