In a slow cooker, add chicken, heavy cream, butter, and broth. Season with garlic powder, Italian seasoning, salt, and pepper.
Cook on high for 2 hours, until chicken is cooked through. Transfer to a plate and shred with two forks, then set aside.
Add rigatoni and Parmesan to slow cooker, and cook until rigatoni is tender, 20 to 25 minutes more.
Return chicken to slow cooker and toss to combine. Garnish with parsley before serving.
