Melt butter in heavy saucepan or Dutch oven. Add onion and celery; cook and stir until crisp-tender.
Add broth, milk, salt and pepper; bring just to a boil, stirring constantly. Add cubed potatoes; reduce heat to medium heat. Simmer 5 minutes, stirring frequently. Add in the cheddar soup, stirring it into the soup mixture.
Serve with potato toppers and sour cream. If you want to add more cheese on top, use cheddar cheese on top.