Seafood Thermidor

In a large saucepan, saute onion in 1 tablespoon butter until tender. Combine soup mix and flour; stir into onion until blended. Gradually whisk in milk. Stir in wine or broth and lemon juice. Bring to a boil; cook and stir for 1-2 minutes or until thickened. , Add cod; cook for 1-1/2 minutes. Stir in shrimp; cook 1 minute longer or until fish flakes easily with a fork and shrimp turn pink. Remove from the heat; stir in mozzarella cheese and parsley until cheese is melted. , Transfer to a 3-cup baking dish coated with cooking spray. Melt remaining butter; toss with bread crumbs and Parmesan cheese. Sprinkle over seafood mixture. Broil 4-6 in. from the heat for 3 minutes or until topping is golden.