In a large pot of boiling salted water, cook penne until al dente according to the package instructions. Reserve about 1 cup of pasta water. Drain. Set aside.

Place chicken in a large bowl. Add cajun seasoning. Toss to coat. Season with salt and pepper. 

Meanwhile, heat oil in a large frying pan over medium heat. Add chicken in a single layer. Fry for about 5-6 minutes or until cooked through. Remove from pan. Set aside.

To the same pan, add butter.

When butter is melted, add garlic. Sauté, stirring, for about 2 to 3 minutes or until fragrant.

Gradually stir in cream. Add lemon zest. Simmer for about 2 to 3 minutes.

Whisk in parmesan. Season with salt and pepper. Let the sauce simmer for 1 to 2 minutes to thicken slightly.

Add cooked penne and 2 tablespoons chopped parsley leaves. Toss. If the sauce is too thick, add reserved pasta water, one tablespoon at a time. 

To serve, divide pasta among 4 serving bowls. Top with sliced cooked chicken, tomatoes, parmesan and chopped parsley.

Serve with your favorite side - garlic toast, salad, or roasted vegetables.