In a large skillet, heat olive oil over medium heat. Add the chicken pieces, Cajun seasoning, salt, and black pepper. Cook until the chicken is browned and cooked through, about 5-7 minutes. Remove from heat and set aside.

In the same skillet, add the diced onion, garlic, and bell pepper. Sauté until the vegetables are softened, about 3-4 minutes.

Add the diced tomatoes (with their juice) and chicken broth to the skillet. Stir to combine.

Add the penne pasta to the skillet, making sure it is submerged in the liquid. Bring to a boil, then reduce heat to low, cover, and simmer for 12-15 minutes, or until the pasta is tender. Stir occasionally.

Once the pasta is cooked, stir in the heavy cream and shredded cheddar cheese. Cook for an additional 2-3 minutes until the cheese is melted and the sauce is creamy.

Add the cooked chicken back to the skillet and stir to combine. Cook for another 2 minutes to heat through.

Serve hot, garnished with chopped parsley.