Prepare the Chicken: Place the chicken breasts (or thighs) in the bottom of the slow cooker. Season with salt, pepper, and 1 teaspoon of dried Italian seasoning.
Add Vegetables: Add the chopped onion, garlic, carrots, and celery into the slow cooker. Pour in the chicken broth and diced tomatoes (with their juices). Stir everything together.
Cook the Soup: Cover the slow cooker and set it on low for 6-7 hours, or on high for 3-4 hours. The chicken should be cooked through and easy to shred.
Shred the Chicken: Once the chicken is cooked, remove it from the slow cooker and shred it with two forks. Return the shredded chicken to the soup.
Add Cream and Tortellini: Stir in the heavy cream or half-and-half, then add the tortellini to the slow cooker. Cover and cook on high for 20-30 minutes, or until the tortellini is tender and cooked through.
Add Greens (Optional): If you’re using spinach or kale, stir it into the soup just before serving. The heat from the soup will wilt the greens perfectly.
Serve: Ladle the soup into bowls and sprinkle with grated Parmesan cheese if desired. Taste for seasoning and add more salt and pepper, if needed.
