Season the Chicken: In a bowl, toss the chicken pieces with Cajun seasoning to evenly coat.
Assemble in the Slow Cooker: Add the seasoned chicken, bell peppers, diced tomatoes, and minced garlic to the slow cooker. Pour in the chicken broth and heavy cream, stirring to combine.
Cook Low and Slow: Cover and cook on low for 4-5 hours or high for 2-3 hours until the chicken is tender.
Add Pasta and Cheese: Stir in the uncooked penne pasta and Parmesan cheese. Cook on high for an additional 30 minutes, or until the pasta is tender.
Season and Serve: Adjust seasoning with salt and pepper if needed. Garnish with fresh parsley and serve hot.