Start by patting the chicken breasts dry with paper towels. Sprinkle both sides of the chicken with the Cajun seasoning.
In a large skillet, melt 2 tablespoons of unsalted butter over medium heat. Add the seasoned chicken breasts and cook for about 6-7 minutes on each side until golden brown and cooked through. Remove and let it rest.
In the same skillet, add the remaining 2 tablespoons of butter. Once melted, pour in the heavy cream, stirring to combine. Add the lemon pepper, salt, black pepper, and garlic powder. Simmer for about 5 minutes.
Add the cooked penne pasta to the skillet, tossing it in the creamy sauce until well coated. Add pasta water if too thick.
Slice the cooked chicken into strips and add it to the pasta along with the diced tomatoes. Toss gently until well mixed.
Remove from heat, sprinkle fresh Parmesan cheese on top, and serve immediately.
