Recipe by: AMC Collection, Cooking with the Asheville Mushroom Club, p. 32

Place stock in a heavy-bottomed soup kettle, and bring to a slow simmer over medium heat. Meanwhile, over medium-high heat, heat butter and olive oil in medium sized saucepan. When foam has subsided, add garlic and chopped onion. Saute, stirring occasionally, until the onion is transparent, about 1 minute. Add fresh mushrooms and saute, stirring frequently until mushroom liquid has evaporated and slices begin to brown. Add to simmering stock, together with tomatoes, salt and pepper. Simmer very gently, uncovered, until flavors are well-blended and slices are tender, at least 30 minutes. (Alternatively, soup can be slow-cooked in a crock pot for several hours.) Just before serving, stir parsley into soup. Beat eggs with a fork in a small bowl until blended. Add beaten eggs slowly to simmering soup, beating constantly with a long-handled fork. Eggs will spin out in threads. To serve, place a piece of toasted bread in each of four soup plates. Ladle hot soup over bread slices. Sprinkle with freshly grated Parmgiano-Reggiano, and serve immediately, accompanied by grated cheese. Yields 4 - 6 servings.