Lean Bechamel with Cream

Put ten ounces of butter in a saucepan with half a pound of onions cut in three-sixteenth inch squares, half a pound of carrots cut in quarter inch squares and a quarter of a pound of celery root cut the same; fry the whole on a slow fire, adding a quarter of a pound of flour. Let cook for a few minutes, then moisten with two quarts of boiled milk; stir with a spatula until boiling point; add a bunch of parsley garnished with two bay leaves and as much thyme, season with salt and whole peppers, and let cook slowly for one hour, then skim off the fat and reduce the sauce by adding to it gradually one pint of cream; strain the whole into a high saucepan through a tammy (No. 159) and keep warm in a bain-marie, setting a few pats of fresh butter on top.