Pat the chicken dry and place it in a large bowl. Drizzle with olive oil and sprinkle with Cajun seasoning, garlic powder, onion powder, smoked paprika, salt, and pepper. Rub the spices into the chicken until well coated.

Heat a large skillet over medium heat. Add a little oil if needed and sear the chicken for 2 to 3 minutes on each side until lightly browned.

Transfer the seared chicken to the bottom of the slow cooker and scatter sliced bell pepper, sliced onion, and minced garlic evenly over the chicken.

Pour in the diced tomatoes with juices and chicken broth into the slow cooker, without stirring.

Cover and cook on low for 4 to 5 hours or on high for 2 to 3 hours, or until the chicken reaches 165°F and is easy to shred.

Remove the chicken and shred it with two forks, then return to the slow cooker and stir to combine.

Stir in the heavy cream and grated Parmesan until melted and the sauce is silky. Taste and adjust seasoning.

Cook the pasta according to package directions until al dente. Drain thoroughly and add to the slow cooker, stirring to coat in the sauce.

Let the combined pasta and sauce heat on low for 15 to 20 minutes to meld flavors and serve garnished with fresh parsley.