How to Make It
Cook bacon in a Dutch oven over medium-high, stirring often, until bacon is crisp, about 10 minutes. Transfer bacon to a plate lined with paper towels to drain.
Add onion and celery to bacon drippings over medium-high; cook, stirring constantly, until softened, about 5 minutes. Add cauliflower, salt, and pepper; cook, stirring often, for 2 minutes. Add chicken stock, and bring to a boil. Reduce heat to medium; cover and cook until cauliflower is tender, 10 to 15 minutes. Uncover and simmer 10 minutes.
Transfer soup to a blender. Remove center piece of blender lid (to allow steam to escape); secure lid on blender, and place a clean towel over opening in lid. Process for 30 seconds or until desired consistency. Return soup to Dutch oven over medium-low. Stir in cream, and bring to a low simmer. Stir in 1 cup of the cheese until melted; remove from heat. Top each serving with sour cream, scallions, cooked bacon, and remaining cheese.