Preheat your oven's broiler. Grease a broiling pan or line pan with aluminum foil.
In a small bowl, mix together the Parmesan cheese, butter, mayonnaise and lemon juice. Season with dried basil, pepper, onion powder and garlic 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 for a couple more minutes. Remove the fillets from the oven and cover them with the Parmesan cheese mixture on the top side. 3. . . .cover them with the Parmesan cheese mixture on the top side. Sprinkle with panko bread crumbs. Broil for 2 more minutes or until the topping is browned and fish flakes easily with a fork. (Shift pan further from heat if crumbs start to brown too quickly.)