Crumble sausage into large skillet, add onion.
Cook and stir over medium heat until meat is no longer pink.
Add garlic, cook 1 minute longer. Stir in the broth, water and tomatoes. Bring to a boil.
Add tortellini, return to boil. Cook for 7-9 minutes or until tender, stirring occasionally.
Reduce heat, add the spinach, basil, pepper and pepper flakes.
Cook 2-3 minutes longer or until spinach is wilted.
Serve with cheese if desired.
Yield:6 servings (2 quarts).