Preheat oven broiler. Grease broiling pan or line with aluminum foil.

Mix Parmesan cheese, butter, mayonnaise, and lemon juice together in a small bowl.

Season fish with pepper and salt.

Arrange fillets in a single layer on prepared pan.

Broil a few inches from the heat for 2 to 3 minutes. Flip fillets over and broil for 2 or 3 minutes more. Remove fillets from oven and cover with Parmesan mixture on top side.

Broil until fish flakes easily with a fork, about 2 minutes.

Preheat oven to 400 F (200 C).

To prepare the brussels sprouts, cut off the brown ends and remove any yellow outer leaves.

In a medium bowl, mix them with the oil, salt, and pepper until evenly coated.

Spread them out evenly on a sheet pan and roast for about 30-35 minutes until tender on the inside. Keep an eye on them while cooking and shake the pan every so often so that they brown evenly.

Remove from oven and serve.