In a large pot, heat olive oil over medium heat. Add sausage and cook until browned. Drain excess fat if needed.
Stir in chopped onion and garlic; sauté for 2–3 minutes until softened.
Pour in chicken broth and diced tomatoes. Stir in Italian seasoning, salt, and pepper. Bring to a boil.
Add tortellini and cook for 5–7 minutes or until tender.
Stir in spinach and cook until wilted.
Lower the heat and stir in heavy cream. Simmer for 2–3 more minutes.
Serve hot with freshly grated Parmesan on top.