Preheat the oven to 350°F (175°C).
In a large pot, bring salted water to a boil. Add the penne pasta and cook according to package instructions until al dente. Drain and set aside.
In a large skillet over medium heat, add the olive oil. Once hot, add the diced chicken, Cajun seasoning, salt, and pepper. Cook until the chicken is browned and cooked through, about 5-7 minutes.
Add the diced onion, minced garlic, and red bell pepper to the skillet. Sauté until the vegetables are softened, about 4-5 minutes.
Pour in the chicken broth and bring to a simmer. Stir in the softened cream cheese until melted and fully incorporated.
In a large mixing bowl, combine the cooked penne pasta with the chicken cream cheese mixture. Mix well to ensure even coating.
Transfer the pasta mixture into a greased 9x13 inch baking dish. Top with shredded cheddar and mozzarella cheeses.
Bake in the preheated oven for 20-25 minutes, or until the cheese is bubbly and golden brown.
Remove from the oven and let cool for a minute before serving. Garnish with fresh parsley if desired.