This is one of the specialities of Ile-de-France, and is a delicious way of cooking whiting or cod.
Put a small piece of butter, worked with chopped parsley and shallot, in each whiting, and lay the fish in a buttered fireproof dish, on a layer of chopped shallots and parsley. Season with salt and pepper, add the bayleaf, the white wine, the mushrooms, previously cooked in butter and chopped. Dot with pats of butter, and cook for about 20 minutes in a moderate oven. Serve in the same dish in which they were cooked.