The Book of Household Management by Mrs. Beeton

474. INGREDIENTS.--1/2 pint of button mushrooms, 1/2 pint of good beef

gravy, No. 435, 1 tablespoonful of mushroom ketchup (if at hand), thickening of butter and flour. _Mode_.--Put the gravy into a saucepan, thicken it, and stir over the fire until it boils. Prepare the mushrooms by cutting off the stalks and wiping them free from grit and dirt; the large flap mushrooms cut into small pieces will answer for a brown sauce, when the buttons are not obtainable; put them into the gravy, and let them simmer very gently for about 10 minutes; then add the ketchup, and serve. _Time_.--Rather more than 10 minutes. _Seasonable_ from August to October. _Note_.--When fresh mushrooms are not obtainable, the powder No. 477 may be used as a substitute for brown sauce. WHITE MUSHROOM SAUCE, to serve with Boiled Fowls, Cutlets, &c. I.