Heat a large heavy bottomed pot or dutch oven over medium heat. Spray with cooking spray and add celery, onion, carrots, and salt/pepper stirring occasionally for about 5-10 until tender. Add rosemary, garlic, and crushed red pepper and cook for 1-2 more minutes.
Turn down to low and add shredded rotisserie chicken breast, lemon zest/juice, chicken broth, and bullion. Put a lid on to simmer.
If you like a thicker, "creamier" broth, blend steamed cauliflower. If it's too thick, Scoop out a cup of broth from your soup to blend it with the cauliflower 'till nice and smooth. Add pureed cauliflower/broth back into soup. Finish with extra fresh rosemary and a handful of fresh minced parsley. Simmer 'till dinner!