Reserve 2 tablespoons bacon grease.
Saute chopped onion and celery in bacon grease until translucent (3-5 minutes).
Add chicken broth and milk.
Bring to simmer.
Cook until almost tender, about 15 minutes.
Add roasted cauliflower and cook an additional 5-10 minutes.
Puree with immersion blender.
Add salt and pepper to taste.
Top with shredded cheese and bacon.