Place the chicken breasts in the slow cooker. Add the cream of chicken soup, chicken broth, cream cheese cubes, garlic powder, salt, and pepper.
Cover and cook on low for 4 to 5 hours until the chicken is tender enough to shred.
Shred the chicken directly in the slow cooker and stir to combine with the sauce.
Stir in the uncooked rice, drained spinach, chopped artichoke hearts, and Parmesan cheese until everything is evenly mixed.
Cover and cook on low for 45 to 60 minutes more, stirring once halfway through, until the rice is tender and has absorbed the liquid.