Step 1: Preheat oven to 375°F (190°C) and grease a 9×13-inch baking dish.
Step 2: Cook penne pasta according to package directions until al dente, drain, and set aside.
Step 3: Season chicken pieces with Cajun seasoning, salt, and pepper.
Step 4: Heat olive oil in a large skillet over medium-high heat. Add chicken and cook until browned and cooked through, about 6-8 minutes. Remove chicken and set aside.
Step 5: In the same skillet, add onion, garlic, and bell pepper. Sauté until softened, about 5 minutes.
Step 6: Reduce heat to medium. Add chicken broth, cream cheese, and heavy cream. Stir until cream cheese is melted and sauce is smooth.
Step 7: Return chicken to the skillet. Add cooked pasta and stir to combine. Season with additional salt and pepper if needed.
Step 8: Transfer mixture to the prepared baking dish. Top evenly with mozzarella and Parmesan cheeses.
Step 9: Bake for 20-25 minutes, until cheese is melted and bubbly.
Step 10: Let cool for 5 minutes, garnish with fresh parsley, and serve hot.