Saute onion, carrots and celery in 1 tablespoon butter or 1 tablespoon olive oil.
Stir in basil and parsley.
Add chicken broth and diced potatoes.
Cook over medium heat until potatoes are tender, 10-15 minutes.
Separately, mix melted butter and flour together with a fork and add to soup.
Bring to a boil and mix well.
Turn heat down, then add ham, cheese, milk, salt and pepper.
DO NOT BOIL AFTER ADDING MILK AND CHEESE.
Blend in 1/4 cup sour cream.