Place bacon in a large skillet and cook over medium-high heat, turning occasionally, until crisp, about 10 minutes. Remove from skillet and crumble. Reserve drippings.
Place potatoes in a pot; cover with water. Bring to a boil. Reduce heat to medium-low. Cook, covered, until tender, 15 to 20 minutes. Drain.
Melt butter in a large skillet over medium-high heat. Add onion and garlic; saute until onion is translucent, about 5 minutes. Stir in bacon crumbles, reserved bacon drippings, flour, salt, and pepper. Reduce heat; add the boiled potatoes, half-and-half, and chicken broth. Simmer until thickened, about 5 minutes. Add sour cream and 1 cup Cheddar cheese; cook and stir until heated through, about 5 minutes. Garnish soup with remaining Cheddar cheese and parsley.
