Slow-Cooker Cajun Alfredo

In a slow cooker, add chicken, heavy cream, butter, and broth. Season with Cajun seasoning, paprika, onion powder, garlic powder, salt, and pepper. Cook on high for 2 hours, or until chicken is cooked through.  Transfer to a work surface, let cool 10 minutes, then thinly slice chicken. Meanwhile, add penne, sausage, and Parmesan to slow cooker, and cook until penne is tender, 25 to 30 minutes more.   Add tomatoes and scallions, and stir to combine. Season with salt and pepper.  Return chicken to slow cooker. Garnish with more parmesan and parsley and serve.