Saute diced onion in some oil in your soup pot over medium heat.
Add broth, tomatoes, cream, garlic, salt, and thyme. Bring to a boil and then turn heat down and let soup simmer for at least 20 minutes, but the longer the better.
Add tortellini and cook on medium heat for 10-15 minutes or until pasta is tender.
Add spinach 5 minutes before serving to allow it to wilt.
Garnish with shredded parmesan cheese.