4 tablespoons butter
4 cups thinly sliced onions
5 cups beef bouillon or broth
1 teaspoon Worcestershire sauce
1 teaspoon salt
1/4 teaspoon pepper

Preheat frying pan to 300°F. Slowly sauté onions in melted butter to a deep brown. Add bouillon, Worcestershire, salt and pepper. Cook, covered, very slowly at 225°F for 1 hour. Serve with toast cubes sprinkled with Parmesan cheese.