Butterfly the chicken breasts into even fillets and place them in a lightly greased slow cooker.
Season lightly with salt and pepper if desired.
Add heavy cream, chicken broth, butter, cream cheese, and spices over the chicken.
Cover and cook on HIGH for 2 hours or LOW for 3 hours until fully cooked.
Remove the chicken, shred using two forks, and set aside.
Stir the sauce until smooth and creamy.
Add 1/2 cup parmesan cheese and penne pasta into the Crock Pot Chicken Alfredo mixture.
Cook on HIGH for 30 minutes, adding the shredded chicken back after 20 minutes.
Once pasta is tender, garnish with remaining parmesan and parsley. Serve warm.