1. Prepare Oven and Broiler Pan:
- Adjust an oven rack so it is about 4 inches from the broiler heat source.
- Preheat the oven’s broiler on the HIGH setting.
- Line a broiler pan (or a sturdy baking sheet) completely with aluminum foil for easy cleanup.
2. Make the Parmesan Topping:
- In a small mixing bowl, combine the ½ cup grated Parmesan cheese, ¼ cup softened butter, 3 tablespoons mayonnaise, 2 tablespoons fresh lemon juice, ¼ teaspoon dried basil, ¼ teaspoon ground black pepper, ⅛ teaspoon onion powder, and ⅛ teaspoon celery salt.
- Mix with a fork or small spatula until all the ingredients are thoroughly combined and form a somewhat spreadable paste. Set aside.
3. Prepare and Arrange Tilapia:
- Pat the tilapia fillets dry with paper towels. If desired, lightly season the fillets on both sides with a pinch of salt.
- Arrange the tilapia fillets in a single layer on the prepared foil-lined broiler pan. Do not overcrowd; use two pans if necessary.
4. Initial Broil:
- Carefully place the broiler pan with the tilapia under the preheated broiler.
- Broil for approximately 2-3 minutes on the first side.
- Using a fish spatula, carefully flip the tilapia fillets over. Broil for another 1-2 minutes on the second side. The fish will be partially cooked but not yet fully opaque. (Total initial broil about 4 minutes, flipping halfway through, as per original directions).
- Remove the pan from the oven.
5. Apply Topping and Finish Broiling:
- Carefully and evenly spread the prepared Parmesan mixture over the top of each partially broiled tilapia fillet.
- Return the pan to the oven under the broiler.
- Broil for about 2 more minutes, watching very closely. The topping should become browned and bubbly, and the fish should flake easily with a fork and be opaque all the way through.
- Be extremely careful not to overcook the fish or burn the topping. Broilers work very quickly!
6. Serve:
- Once the topping is golden and the fish is cooked, carefully remove the pan from the broiler.
- Serve the Broiled Tilapia Parmesan immediately while hot. Enjoy!