Place the chicken breasts in the bottom of your slow cooker. Add the crushed tomatoes, tomato sauce, broth, garlic, onion, and all the seasonings. Give everything a gentle stir to combine.
Cover and cook on low for 6 hours or high for 3–4 hours, until the chicken is tender and cooked through.
Remove the chicken from the slow cooker and shred it with two forks, then return it back to the soup.
Stir in the uncooked pasta, cover, and cook on high for 20–25 minutes, just until the pasta is tender.
Add the heavy cream, mozzarella, and Parmesan, then stir until everything melts together into a rich, creamy soup. Taste and adjust the seasoning as needed.
Ladle into bowls and garnish with fresh parsley and a sprinkle of extra Parmesan or a handful of croutons for crunch.
