11.In a skillet, cook bacon slices over medium heat, turning occasionally, until brown and crispy. Remove bacon from skillet and reserve bacon grease in skillet.
2. Drain cooked bacon on paper towels and then refrigerate for further use as topping.
3. In same skillet (bacon was fried in previously), fry the onion in the remaining bacon grease over medium heat for 4 or 5 minutes, stirring frequently until onion is tender.
4. Spray 6 quart crock pot with cooking spray and add onion, potatoes, celery, carrots (optional), broth, salt, and pepper..stir them together.
5. Cover and cook on LOW setting for 6-7 hours.
6. In small bowl, beat flour and half-and-half with wire whisk until well blended and lump free.
7. Stir the flour mixture into the soup.
8. Increase heat setting to HIGH setting, then cover, and cook for another 30 minutes longer or until thickened.
9. Stir in cheese until well melted and crumble bacon and sprinkle it over top. Enjoy!