Bring a large pot of salted water to a boil. Add the penne pasta and cook according to package instructions until al dente. Drain and set aside.
In a skillet over medium-high heat, add the olive oil. Once hot, add the diced onion and bell pepper, sautéing for about 3-4 minutes until softened.
Add the minced garlic and chicken pieces to the skillet, and sprinkle the Cajun seasoning over the top. Cook for about 5-7 minutes, stirring occasionally, until the chicken is browned and cooked through.
Pour in the chicken broth and bring to a simmer. Let it cook for about 3 minutes, allowing the flavors to meld.
Reduce the heat to low and add the heavy cream and Parmesan cheese to the skillet. Stir until the cheese has melted and the sauce is creamy.
Add the cooked penne pasta to the skillet and toss until the pasta is well coated in the creamy sauce. Season with salt and pepper to taste.
Remove from heat, garnish with fresh parsley, and serve hot.