01 - In a large pot over medium heat, cook the chopped beef bacon until crispy. Remove with a slotted spoon and set aside, leaving approximately 2 tablespoons of rendered fat in the pot. Discard excess fat.
02 - Add unsalted butter to the pot. Sauté the finely chopped onion, celery, and diced carrot for 5 minutes until softened. Add minced garlic and cook for an additional minute.
03 - Add the peeled and diced potatoes to the pot. Sprinkle the flour evenly over the vegetables and potatoes (if using). Cook for 2 minutes, stirring constantly to blend and slightly toast the flour.
04 - Pour in the low-sodium chicken broth and bring the mixture to a gentle boil. Reduce heat and simmer uncovered for 15 to 20 minutes, or until the potatoes are tender when pierced.
05 - Lower the heat to medium-low. Stir in whole milk and heavy cream. Allow the soup to simmer gently for 5 minutes without reaching a boil, ensuring it remains creamy.
06 - Remove the pot from heat. Use an immersion blender to puree the soup until it achieves a creamy texture with some chunks remaining. Alternatively, transfer half the soup to a blender, puree, and return it to the pot.
07 - Stir shredded sharp cheddar cheese into the hot soup until fully melted and smooth. Season to taste with salt and freshly ground black pepper.
08 - Ladle the soup into bowls. Garnish with the crispy beef bacon, extra shredded cheddar cheese, and chopped fresh chives or green onions, if desired.