Add the sausage meat, breaking them with a rubber spatula or wooden spoon until broken into some large some small pieces.Allow them to brown for 2-3 minutes. Drain off any excessive grease.
Reheat the pot add the onions, garlic and cook until the onion is translucent, about 5 minutes. There's no need to add oil as some fat from the sausage will remain.
Add in the crushed tomatoes, tomato paste, dried herbs and chili flakes if using. Stir well until fully incorporated. Add the chicken stock, bring to a boil, season and drop the heat to a simmer, cook until slightly reduced, about 10 minutes.
Stir in the tortellini, and cream. Cook until the pasta is heated through and tender, 2-3 minutes. Take it off the heat, stir in the spinach until just wilted.
Ladle the soup into bowls. Sprinkle with Parmesan, if desired, before serving.