6 cups beef broth
    1-1/2 c thinly sliced onion

    Saute in 3 T butter until dark brown, but not burned. Add beef
    broth to onions and simmer 45 minutes.

    For serving: top each serving with a slice of French bread and
    Parmesan cheese. Shredded Swiss or mozzarella cheese may be
    placed on top, then broiled to melt. Worcestershire sauce may be
    added to the soup as desired. Source: Bea Spaniol