1. Cook the bacon in a large pot until crispy, then remove and set aside.
2. Sauté the chopped onions, carrots, and celery in the bacon grease until softened.
3. Add the peeled and diced russet potatoes to the pot.
4. Season with salt, pepper, and Cajun spice for extra flavor.
5. Pour in the chicken or vegetable broth until the potatoes are fully covered.
6. Bring the mixture to a boil, then reduce heat and let it simmer until the potatoes are fork-tender.
7. Carefully blend a portion of the soup using an immersion blender or by transferring some to a blender, then return it to the pot for a creamy texture.
8. In a separate pan, make a roux by whisking flour with melted butter until smooth.
9. Slowly whisk in the milk and heavy cream, cooking until thickened.
10. Pour the creamy mixture into the pot and stir well.
11. Add the cooked bacon back into the soup, reserving some for topping.
12. Stir in chopped parsley and shredded cheese until melted and combined.
13. Taste and adjust seasoning if needed.
14. Serve hot and garnish with crumbled bacon, shredded cheese, diced green onions, or sour cream as desired.
15. Pair with side dishes like grilled cheese sandwiches, hearty bread, or a fresh chopped salad for a complete meal.