Bring a large pot of salted water to a boil and cook the penne according to package directions until al dente. Reserve half a cup of pasta water before draining. Drain and set aside. Do not rinse the pasta.

Heat olive oil in a large skillet over medium-high heat. Add the sliced chicken and coat with Cajun seasoning. Cook for 5 to 6 minutes, turning once, until golden brown and cooked through.

Reduce heat to medium. Add minced garlic and stir for about 30 seconds until fragrant. Do not let it brown.

Pour in heavy cream and stir to combine. Let it simmer for 2 to 3 minutes until slightly thickened.

Add the grated Parmesan and stir until melted and smooth. Add a splash of reserved pasta water if needed to adjust sauce thickness.

Add the cooked penne to the skillet and toss until fully coated. Season with salt and pepper and serve immediately with fresh parsley on top.