1. In a skillet over medium heat, brown the Italian sausage, breaking it up, until fully cooked, about 6–8 minutes.

2. Add the chopped onion and minced garlic to the skillet and sauté until translucent, about 2–3 minutes.

3. Transfer the sausage mixture to the slow cooker. Add diced tomatoes with juices, chicken broth, Italian seasoning, crushed red pepper flakes, and black pepper. Stir to combine.

4. Cover and cook on low for 4 hours.

5. About 30 minutes before serving, stir in the softened cream cheese until melted and smooth.

6. Add the cheese tortellini and fresh spinach to the slow cooker and cook until the tortellini is tender, about 30 minutes.

7. Taste and adjust seasoning with salt and black pepper.

8. Ladle the soup into bowls and serve hot.