Preheat your oven to 375°F (190°C).

Cook the penne pasta according to package instructions until al dente. Drain and set aside.

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

Add the onion, garlic, and bell pepper to the skillet. Sauté for an additional 3-4 minutes until the vegetables are softened.

Stir in the diced tomatoes and heavy cream. Bring the mixture to a simmer and cook for another 2-3 minutes.

In a large mixing bowl, combine the cooked pasta, chicken mixture, half of the mozzarella cheese, and half of the Parmesan cheese. Mix well to combine.

Transfer the pasta mixture to a greased 9x13-inch baking dish. Top with the remaining mozzarella and Parmesan cheese.

Bake in the preheated oven for 25-30 minutes, or until the cheese is bubbly and golden brown.

Remove from the oven and let cool for a few minutes before serving. Garnish with chopped parsley if desired.