Preheat broiler. In a skillet cook sausage until brown, about 5 minutes. Add mushrooms and onion; cook, stirring frequently, until mushrooms are tender, about 5 minutes. Add beef broth; simmer covered about 5 minutes. Place 4 heat-proof serving bowls on a shallow baking pan; ladle soup into bowls. Top each bowl with a slice of bread; sprinkle with cheese. Broil 3 to 5 inches from heat until cheese melts, about 2 minutes. Carefully remove from broiler and serve.
Per Serving: 406 Calories (53.4% from fat); 24g Fat (10g Sat, 10g Mono, 3g Poly); 26g Protein; 21g Carbohydrate; 2g Dietary Fiber; 62mg Cholesterol; 1694mg Sodium. Food Exchanges: 1/2 Grain (Starch); 3 Lean Meat; 1 1/2 Vegetable; 3 1/2 Fat.