
Crumble the sausage into a Dutch oven, and add the onion. Cook and stir over medium heat until the meat is no longer pink. Add the garlic, and cook for one minute longer. Editor's Tip: The sausage casings are edible, but we remove them to give the meat a crumbly texture.
Stir in the broth, water and tomatoes. Bring the mixture to a boil. Editor’s Tip: To give the soup a richer character, substitute additional broth for the water.
Add the tortellini, and return the mixture to a boil. Cook for five to eight minutes or until almost tender, stirring occasionally.
Reduce the heat, and add the spinach, basil, pepper and pepper flakes. Cook for two to three minutes longer or until the spinach is wilted and the tortellini are tender. Serve with Parmesan cheese if desired.