Start by seasoning the chicken breasts with 2 teaspoons of Cajun seasoning, salt, black pepper, and garlic powder. Make sure to coat the chicken evenly for the best flavor.
In a large skillet, heat 2 tablespoons of butter over medium heat. Once melted, add the seasoned chicken breasts. Cook for about 6-7 minutes on each side, or until the chicken is cooked through and has a nice golden-brown color. Remove the chicken from the skillet and let it rest for a few minutes before slicing it into strips.
In the same skillet, add the remaining 2 tablespoons of butter. Once melted, pour in the heavy cream and stir well. Add the remaining Cajun seasoning and lemon pepper seasoning to the cream. Bring the mixture to a gentle simmer, allowing it to thicken slightly for about 5-7 minutes.
Add the cooked penne pasta and diced tomatoes to the skillet, tossing them in the creamy sauce until well coated. Add the sliced chicken on top and gently mix to combine all the ingredients evenly.
Finally, sprinkle the fresh shredded Parmesan cheese over the pasta, allowing it to melt into the sauce. Serve hot, garnished with additional diced tomatoes or a sprinkle of extra Cajun seasoning if desired.