Slice mushroom caps and chop stems. Set aside while you saute onion and celery in butter in a large heavy skillet or dutch oven 3 minutes. Add parsley and saute 3 minutes stirring with a wooden spoon. Add mushrooms. Sprinkle on salt, paprika and flour. Stir constantly until well blended. Add broth slowly. Bring to a boil. Lower heat and simmer 10 min.