Bring a large pot of salted water to a rolling boil. Add penne pasta and cook for 10-12 minutes until al dente. Reserve 1 cup of pasta water before draining.

Heat 2 tablespoons of olive oil in a large skillet over medium-high heat. Season chicken breast with Cajun seasoning, adding to the skillet once oil is shimmering. Cook for 4-5 minutes on each side until golden brown. Remove and let it rest.

In the same skillet, lower the heat and add shrimp. Sauté for 2-3 minutes until pink and opaque. Remove and set aside with chicken.

Add Andouille sausage to the skillet. Cook for about 2 minutes until browning. Add bell peppers, onion, and garlic, sautéing for another 4 minutes until tender and fragrant.

Pour in heavy cream and stir to combine, letting it simmer for 2-3 minutes. Gradually add Parmesan cheese until melted and sauce is smooth. Adjust seasoning as desired.

Return chicken and shrimp to the skillet with drained pasta. Toss gently to coat the pasta in sauce and heat through for 1-2 minutes.

Remove from heat and garnish with chopped parsley. Serve immediately.