Prepare the Base: In your slow cooker, combine the browned sausage, chopped onion, minced garlic, and diced tomatoes.
Add Broth and Seasonings: Pour in the vegetable broth and mix in the dried basil, oregano, salt, and pepper to taste.
Cook Slowly: Cover the slow cooker and let the soup cook on low for 6-7 hours or on high for 3-4 hours.
Add Tortellini and Spinach: Stir in the tortellini and fresh spinach about 30 minutes before the cooking time is up.
Incorporate Cream: Pour in the heavy cream, stir thoroughly, and continue cooking on high for an additional 25-30 minutes, or until the tortellini are tender.
Serve: Ladle the soup into bowls, sprinkle with grated Parmesan cheese, and enjoy!