1 lb. frozen haddock fillets (can also use flounder)
1/4 c. onion, finely chopped
5 tbsp. butter
2 tbsp. all-purpose flour
1/4 tsp. salt
1/8 tsp. pepper
1 c. milk
1 c. (4 oz.) Sharp cheese, shredded
1/2 c. milk
1 env. sour cream sauce mix
1 (4 oz.) can mushrooms, sliced
1 c. frozen peas, thawed

In large skillet, barely cover fish with water. Simmer gently until fish flakes with a fork; drain. Break fish into large chunks; set aside.

In large saucepan, cook onion in 2 tablespoons butter until tender but not brown. Blend in flour, salt and pepper. Add milk all at once. Cook, stirring constantly, until mixture thickens and bubbles. Remove from heat. Add cheese; stir until melted. (Reserve some cheese for topping dish).

Using 1/2 cup milk, prepare sour cream sauce mix according to directions. Combine cheese, sauce, fish, mushrooms, peas and sour cream sauce. Place in casserole and top with reserved cheese.

Bake at 400 degrees for 15 to 20 minutes. Serves 6.

Great with baked potato and salad.