Mushrooms au Gratin (Hot)

Peel the mushrooms and cut off their stalks, and place them in a buttered fireproof dish. Peel the stalks and wash them, add the peelings, dry them and cut them up. Make a sauce with 1 oz. of butter, and when melted add ½ oz. of flour, stirring into it ½ pint of milk. Stir well, bring to the boil, and then throw in the chopped stalks, a dessertspoonful of finely-chopped parsley, a teaspoonful of finely-chopped onion, a dusting of pepper, and ½ a teaspoonful of salt. Simmer the sauce until it thickens, strain and add some browning. Pour the sauce over the mushrooms, sprinkle some browned breadcrumbs over the whole, and bake in a quick oven for 10 minutes.