In a bowl, combine sliced chicken with Cajun seasoning. Mix well and let it marinate for at least 15 minutes.
Boil a large pot of salted water and cook the pasta according to package instructions until al dente. Drain and set aside.
In a large skillet, heat olive oil over medium heat. Add the marinated chicken and cook until browned and cooked through, about 6-8 minutes. Remove from the skillet and set aside.
In the same skillet, add the sliced bell pepper and onion. Sauté for about 5 minutes until they soften. Add minced garlic and cook for an additional minute until fragrant.
Pour in the can of diced tomatoes, including their juices. Stir and let it simmer for 2-3 minutes. Add the heavy cream, stir well, and allow to simmer on low heat for about 5 minutes until it thickens slightly.
Return the cooked chicken to the skillet. Add the drained pasta and mix everything together gently until the pasta is well coated in the creamy sauce. Season with salt and pepper to taste.
Plate the pasta and garnish with chopped fresh parsley and a generous sprinkle of grated Parmesan cheese.