Wash one-half pound mushrooms, remove stems, and peel caps. Sprinkle with salt and pepper, dredge with flour, and cook three minutes in a hot frying-pan, with two tablespoons butter. Add one and one-third cups Brown Sauce, and cook slowly five minutes. Sprinkle with three tablespoons grated cheese. As soon as cheese is melted, arrange mushrooms on pieces of toast, and pour over sauce. Garnish with parsley.