01 - Arrange chicken breasts in a single layer at the bottom of the slow cooker.
02 - Whisk together chicken broth, heavy cream, Parmesan, garlic, Italian seasoning, onion powder, salt, and pepper in a medium bowl until fully incorporated.
03 - Pour the sauce mixture evenly over the chicken, ensuring all pieces are coated.
04 - Cover and cook on low setting for 4–6 hours or on high for 2–3 hours until chicken reaches internal temperature of 165°F and is tender.
05 - For thicker consistency, combine cornstarch and water to form slurry. Stir into the slow cooker during the final 30 minutes of cooking.
06 - Transfer chicken to serving plates, spoon creamy sauce over top, and garnish with fresh chopped parsley.