1. Brown the Sausage: In a large pot or Dutch oven, heat the olive oil over medium-high heat. Add the Italian sausage, breaking it up with a spoon as it cooks. Cook until it’s fully browned and no longer pink, about 5-7 minutes. Drain any excess grease from the pot, leaving about a tablespoon for flavor.

2. Saute Aromatics: Add the chopped yellow onion to the pot with the cooked sausage. Saute for 3-5 minutes until the onion softens and becomes translucent. Stir in the minced garlic and cook for another minute until fragrant, being careful not to burn the garlic.

3. Build the Broth: Pour in the chicken broth and add the undrained diced tomatoes. Stir in the dried Italian seasoning, salt, and black pepper. Bring the mixture to a gentle simmer, then reduce the heat to medium-low and let it simmer for 10 minutes to allow the flavors to meld.

4. Cook the Tortellini: Add the refrigerated cheese tortellini to the simmering soup. Cook according to package directions, usually 3-5 minutes, until the tortellini is tender but still firm (al dente).

5. Add Cream and Spinach: Reduce the heat to low. Stir in the heavy cream and the chopped fresh spinach. Cook for just 1-2 minutes, or until the spinach wilts and the soup is heated through. Avoid boiling the soup once the cream is added to prevent it from curdling.

6. Finish and Serve: Remove the soup from the heat. Stir in the grated Parmesan cheese until it melts into the soup. Taste and adjust seasonings if necessary. Ladle into bowls and serve immediately, garnished with extra Parmesan cheese if desired.