HADDOCK À LA CRÈME

Boil the fish in salted and acidulated water. Melt two tablespoonfuls of butter and cook in it two heaping tablespoonfuls of flour. Add four cupfuls of milk and cook until thick, stirring constantly. Season with pepper, salt, grated onion, and minced parsley. Put the fish upon a serving-dish, skin it carefully, and pour the sauce over it. Put a border of mashed potatoes around the fish, rub with melted butter and put into the oven until the potato is brown.