Bring a large pot of salted water to a rolling boil. Add the penne pasta and cook for 10-12 minutes until al dente, then drain and set aside.

Heat 2 tablespoons of olive oil in a large skillet over medium heat. Season the chicken breasts with Cajun seasoning, add to the skillet, and cook for 4-5 minutes until golden brown. Remove from skillet.

In the same skillet, add the shrimp and sauté for 2-3 minutes until pink and opaque. Remove from skillet with the chicken.

Add another tablespoon of olive oil to the skillet. Sauté the sliced sausage for 2 minutes until slightly browned, then add bell peppers, onion, and garlic. Cook for another 4 minutes until tender.

Pour in heavy cream, stir and let simmer for 2-3 minutes until thickened. Gradually stir in Parmesan cheese until melted, adjusting seasoning as needed.

Return chicken and shrimp to skillet along with cooked pasta. Toss gently for 1-2 minutes until well combined and coated in sauce.

Remove from heat, sprinkle with chopped parsley, and serve immediately.