Grate 2 cups of cheddar cheese and set aside. Cook 6 slices of bacon in a skillet until crispy, then transfer to a paper towel-lined plate. Peel and cube 4 large russet potatoes.

Place cubed potatoes in a saucepan and cover with cold water. Add ¾ tsp salt. Bring to a boil, reduce heat, and cook until tender (15-20 minutes). Drain and set aside.

In the same pot used to cook bacon, leave 2 tbsp of bacon drippings. Add 1 chopped onion and sauté for 5 minutes until translucent. Add 3 minced garlic cloves and cook for 1-2 minutes until fragrant.

Stir in 2 tbsp butter until melted, then gradually add ¼ cup of flour, stirring constantly for 1 minute to create a roux.

Slowly add 3 ½ cups of chicken broth, stirring constantly to prevent lumps. Stir in 2 ½ cups of half-and-half and bring to a gentle simmer.

Add the cooked potatoes back into the pot, followed by ¾ cup of sour cream. Stir until smooth. Season with salt and pepper to taste.

Gradually fold in 2 cups of grated cheddar cheese, stirring constantly until melted. Avoid overheating to prevent grainy texture.

Ladle soup into bowls and top with crispy bacon, chopped chives, and additional cheddar cheese if desired.