Place the chicken breasts in the bottom of the Crock Pot. Sprinkle the Cajun seasoning, garlic powder, onion powder, black pepper, and salt evenly over the chicken.
In a separate bowl, mix together the cream of chicken soup, diced tomatoes (with their juice), and chicken broth. Pour this mixture over the seasoned chicken in the Crock Pot.
Cover and cook on low for 6-7 hours or on high for 3-4 hours, until the chicken is cooked through and tender.
Remove the chicken from the Crock Pot and shred it with two forks. Return the shredded chicken to the pot.
Stir in the heavy cream and uncooked penne pasta. Cover and cook on high for an additional 30-40 minutes, or until the pasta is tender.
Once the pasta is cooked, stir in the shredded cheddar cheese until melted and creamy.
Serve hot, garnished with chopped parsley.