In a bowl, mix the Parmesan cheese, butter, mayonnaise, lemon juice, green onions, salt, and hot pepper sauce.
Arrange the halibut fillets in the prepared baking dish.
Broil halibut fillets 8 minutes in the prepared oven, or until easily flaked with a fork. Spread with the Parmesan cheese mixture, and continue broiling 2 minutes, or until topping is bubbly and lightly browned.
