Put two bunches of celery, with the leaves included, in chicken broth (1 qt or more). Do not add water. Add one large onion (whole), four cloves of garlic, and four or five peeled potatoes. Cook for 45 minutes. Remove potatoes and mash on a plate. Blend rest of veggies and broth. Strain. Put liquid back in pot and cook with smashed potatoes for five minutes. Turn off stove. Add evaporated milk. Sprinkle with Parmesan cheese.