In a large soup pot, sauté onions in butter over medium heat until soft and translucent. (If you're using bacon you can cook the bacon right in the soup pot and use some of the bacon grease to sauté the onions).

Add garlic and cook for a minute then add diced potatoes.

Cook for five minutes on medium high, seasoning with salt, pepper, celery salt and cajun seasoning.

Pour in the broth and bring to a gentle boil.

Cook for ten minutes, or until the potatoes start to get tender.

Whisk together the flour and milk, then pour into the soup, cooking for another five minutes.

Remove half the soup and blend in a food processor until completely smooth (you can skip this step if you prefer a thinner soup).

Pour the puréed soup back into the pot and stir to combine.

Stir in the heavy cream and bacon.

Taste soup and add more seasonings as desired.

Heat until soup is good and hot.

Serve garnished with shredded cheese (and more bacon if desired).