Cook 3-4 onions, thinly sliced in 2 tablespoons butter until light browned, about 15 minutes. Add 2 (10 1/2 ounce) cans condensed beef broth, 1 1/4 cups water and 1 teaspoon Worcestershire sauce; simmer 20 minutes.

Sprinkle sliced hard rolls or French bread with Parmesan cheese; broil until lightly browned. Float atop each serving of soup. Serves 4-6.