Creamy Parmesan Sauce for Fish

Name: Creamy Parmesan Sauce for Fish
Prep time: 10 min
Cook time: 10 min
Total time: 20 min
Cuisine: American
Ingredients: 1 teaspoon butter, or as needed; 0.75 cup freshly grated Parmesan cheese; 0.33333334326744 cup butter, softened; 0.25 cup mayonnaise; 0.25 cup chopped green onion; 3 tablespoons lemon juice; 2 teaspoons dried dill weed; 0.25 teaspoon salt; 0.25 teaspoon ground black pepper; 2 dashes hot pepper sauce (such as Tabasco®); 2 pounds cod fillets