Place 1 quart milk, onion, peppercorns, salt and bouquet garni in saucepan and bring slowly to boil. Mix together rice flour and remaining 1/4 cup milk to form smooth paste. Pour into just-boiling milk, stirring briskly until lumps disappear. Simmer over very low heat 20 minutes. Cut tough ends off mushroom stems. Reserve few mushroom slices, if desired, for garnish. Chop remaining mushrooms coarsely, then process in food processor as finely as possible. Strain milk mixture through fine sieve into bowl and then back into saucepan. Add chopped mushrooms and continue simmering 5 minutes. Add whipping cream and Madeira. Pour soup into hot bowls and garnish each with reserved mushroom slices. Makes 4 servings. soup 21