Cook bacon in a large skillet over medium-high heat, turning occasionally, until crisp, about 10 minutes. Transfer to a cutting board; crumble and set aside. Reserve drippings and set aside.

Place potatoes into a pot and cover with water; bring to a boil. Reduce heat to medium-low and simmer until tender, 15 to 20 minutes. Drain and set aside.

Melt butter in the same pot over medium-high heat. Add onion and garlic; sauté until onion is translucent, about 5 minutes. Stir in crumbled bacon, bacon drippings, flour, salt, and black pepper; reduce heat. Add boiled potatoes, chicken broth, and half-and-half; simmer until thickened, about 5 minutes. Add 1 cup Cheddar cheese and sour cream; cook and stir until heated through, about 5 minutes. Garnish soup with remaining 1 cup Cheddar cheese and parsley.