Fry chopped bacon and kielbasa slices over medium heat until bacon is golden brown and kielbasa is slightly crispy.
Using a slotted spoon, scoop meat out of the pot and set to the side.
Add carrots and celery into the soup pot, saute 8 - 10 minutes, until tender.
Stir in onion, garlic, and red pepper flakes, saute for one minute.
Pour chicken broth and one cup of milk into pot and simmer over medium heat.
Add in diced potatoes, cover with a lid, simmer for 5-10 minutes until potatoes are tender.
Whisk together flour and remaining 1/2 cup of milk, slowly pour into soup to thicken.
Return bacon and kielbasa into the pot and stir. Continue to simmer using low-medium heat for 10 minutes.
Stir in the cheese until it melts completely.
Add salt and pepper to suit your personal taste. Garnish soup with parsley before serving.