Cook the penne pasta following the package directions until al dente. Once done, drain the pasta and set it aside for later use.

In a large skillet over medium-high heat, add olive oil and diced chicken. Cook for 7-8 minutes, stirring occasionally, until the chicken is browned and fully cooked. Transfer the cooked chicken to a plate.

Lower the heat to medium and add butter, onion, bell pepper, and garlic to the skillet. Sauté the vegetables for 1-2 minutes until they soften slightly and become fragrant.

Sprinkle Cajun seasoning, salt, and black pepper over the vegetables. Stir and cook for an additional minute to allow the spices to bloom.

Sprinkle flour over the vegetable mixture and stir well. Cook until the flour has absorbed the butter, about 1 minute.

Slowly pour in the chicken broth while whisking continuously to avoid lumps.

Add heavy cream and Rotel diced tomatoes to the skillet. Bring the mixture to a low boil, then reduce the heat and simmer for 8-10 minutes until the sauce thickens, stirring frequently.

Return the cooked chicken to the skillet along with 2 teaspoons of chopped parsley. Stir everything together until well mixed.

Add the cooked pasta and grated parmesan cheese to the skillet. Stir until the pasta is evenly coated in the creamy sauce.

Turn off the heat and let the dish sit for 3-4 minutes before serving to allow the pasta to absorb some of the sauce.

Garnish with the remaining parsley before serving. Enjoy your homemade Cajun Chicken Pasta!