Heat olive oil in a Dutch oven over medium-high heat. Add onion and sausage, and saute for about 7 minutes, or until starting to brown. Add garlic and cook an additional minute or two.
Sprinkle flour over sausage mixture, and stir to coat. Add chicken broth a little at a time, stirring constantly, to form a smooth sauce. Bring to a low boil, and add tortellini.
Simmer pasta in broth mixture for the recommended cooking time on the package, stirring frequently. About three minutes before pasta is done, stir in spinach and cream, and gently stir until the spinach wilts. Add pepper or hot sauce if desired.
Turn off heat, and allow pasta to stand for about 5 minutes before serving. Sauce will still be thin, but it will thicken up as it cools and will be perfect for leftovers.