3/4 c  Unsalted butter

      5    Large onions; thinly sliced

      8 c  Beef broth

      1 t  Chicken stock base

           White pepper
     12 oz Jack cheese

           French or sourdough bread*
  *Note: Bread should be sliced 1-in. thick.
  Melt butter in large kettle, add onions and saute until transparent but
  not browned. Add beef broth and chicken stock base. Cover and simmer 2 to
  3 hours. Remove from heat and refrigerate overnight or several hours.

  Discard chilled surface fat. Reheat and season to taste with white pepper.
  Slice cheese into 12 slices. Lightly toast 12 bread slices and top each
  with 1 slice Jack cheese. Pour soup into individual ovenproof serving
  bowls and top with slice of bread and cheese. Run bowls under broiler just
  until cheese bubbles and is soft but not browned.