Heat olive oil in a large pot or Dutch oven over medium-high heat. Add ground turkey and cook, breaking it up with a spoon, until browned. Drain off any excess fat.
Add chopped onion to the pot and cook until softened, about 5 minutes. Stir in minced garlic and cook for 1 minute more until fragrant.
Pour in the chicken broth, diced tomatoes (with their juice), Italian seasoning, pepper, and salt. Bring the mixture to a boil.
Reduce heat to low, cover, and simmer for 10 minutes to allow the flavors to meld.
Add the tortellini to the simmering soup and cook according to package directions, usually about 5-7 minutes, or until tender.
Stir in the fresh spinach and cook until wilted, about 1-2 minutes.
Taste and adjust seasoning if needed. Ladle soup into bowls and serve hot, topped with grated Parmesan cheese.
Notes
This soup is delicious on its own or served with crusty bread. You can also add other vegetables like carrots or celery for extra nutrition and flavor.