Baked Haddock with White Sauce and Buttered Crumbs

1 lb. Haddock fillets or other firm-fleshed fish like cusk
pinch of paprika
salt and pepper, to taste
1-2 T. fresh lemon juice
4 T. butter, divided
2 T. flour
1 T. dry mustard
1 C. milk, warmed
3/4 C. coarsely ground fresh bread crumbs

Preheat oven to 350

Place fish in a shallow roasting dish or gratin pan.

Season both side with salt, pepper and paprika.  Sprinkle lemon juice over fish.

Meanwhile, make the sauce by melting 2 T. butter in a medium sauce pan.  Whisk in the flour.  Stir until combined, over medium heat for about 2 minutes.  Add, in thirds, the milk, first time off the heat and then add remaining milk on the heat, stirring until well combined.  Add the seasonings, stirring to combine well.  If the sauce is too thick, add more milk or heavy cream.  It should be of pouring consistency, like a moderately thick cream soup.

Pour the sauce over the fish, covering the fillets completely.  Mix the crumbs and remaining 2 T. butter to combine.  Sprinkle over fish.  Bake for about 35 minutes or until sauce if bubbly and fish flakes easily with a fork.