In a soup pot or Dutch oven, brown and crumble the sausage with the onion and garlic over medium-high heat for 6-8 minutes, or until meat is no longer pink.
Stir in Italian seasoning, kale, and stock. Cover and bring to a boil over high heat.
Add tortellini and cook an additional 5-6 minutes.
Serve individual portions topped with shredded Parmesan cheese, if desired.