Place the chicken breasts in the bottom of the slow cooker.
Add the cream cheese cubes, sun-dried tomatoes, chicken broth, minced garlic, Italian seasoning, salt, and black pepper.
Cover and cook on low for 6 hours until the chicken is tender.
Remove the chicken and shred or slice it, then return it to the slow cooker.
Stir in the spinach and Parmesan cheese until the spinach wilts and the sauce turns creamy.