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