01 - Place chicken breasts in the bottom of the slow cooker in a single layer.
02 - In a medium bowl, whisk together chicken broth, heavy cream, Parmesan, garlic, Italian seasoning, onion powder, salt, and pepper until well combined.
03 - Pour the sauce evenly over the chicken.
04 - Cover and cook on low for 4–6 hours, or on high for 2–3 hours, until the chicken is cooked through and tender.
05 - For a thicker sauce, whisk together cornstarch and water to make a slurry. Stir into the slow cooker during the last 30 minutes of cooking.
06 - Once done, serve chicken topped with creamy sauce and garnish with chopped parsley.