In a large Dutch oven or pot, add the sausage and onion and cook over medium-high heat until browned. Add the crushed red pepper and garlic, cook for 30 seconds.
Add the chicken broth, crushed tomatoes, tomato paste, and cauliflower florets. Bring to a boil, reduce to medium heat and simmer for 10 minutes or until cauliflower is tender.
Add the cream, spinach, and salt. Heat over medium heat for 5 minutes or until soup starts to thicken. To make soup creamy mash some of the cauliflower with the back of a serving spoon. The more you mash the creamier it will be but leave some whole florets for texture. Serve with a sprinkle of Parmesan cheese.