Boil the penne pasta in a large pot of salted water according to the package instructions until al dente. Drain, rinse lightly, and set aside.
Toss the bite-sized chicken pieces in a bowl with 1.5 tablespoons of the Cajun seasoning until evenly coated.
Heat the olive oil and butter in a large skillet over medium-high heat. Add the seasoned chicken and sliced red bell pepper to the pan. Cook for 5-7 minutes, stirring occasionally, until the chicken is golden brown and fully cooked through.
Add the minced garlic to the skillet and sauté for 1 minute until fragrant.
Reduce the heat to medium-low. Pour in the chicken broth to deglaze the pan, scraping up any browned bits from the bottom. Stir in the remaining 0.5 tablespoon of Cajun seasoning and the heavy cream.
Let the sauce simmer gently for 2-3 minutes until it begins to thicken. Stir in the grated Parmesan cheese until melted and the sauce is entirely smooth.
Add the cooked penne pasta to the skillet, tossing well to coat the noodles evenly in the creamy Cajun sauce.
Remove from heat, garnish with fresh chopped parsley, and serve immediately.