Begin by bringing a large pot of salted water to a vigorous boil. Add the penne pasta and cook according to the package instructions until al dente, usually about 10-12 minutes. Reserve ½ cup of pasta water, then drain the pasta and set aside.

In a large skillet, heat 2 tablespoons of olive oil over medium-high heat. Season the chicken breast with Cajun seasoning. Add chicken to the skillet and cook for about 4-5 minutes until golden brown and cooked through. Remove and keep warm.

Using the same skillet, add the shrimp and cook for about 2-3 minutes until pink and opaque. Transfer shrimp to the plate with the chicken.

In the same skillet, add more oil if needed and add the sliced andouille sausage. Sauté for about 2 minutes until browned, then add bell peppers, red onion, and garlic. Cook for about 4 minutes until tender and fragrant.

Lower the heat to medium and pour in the heavy cream. Simmer for 2-3 minutes to thicken. Gradually stir in grated Parmesan cheese until melted. Adjust seasoning with salt, pepper, and more Cajun seasoning.

Return cooked chicken and shrimp to the skillet, followed by the drained penne pasta. Toss gently for 1-2 minutes, adding reserved pasta water if needed to reach desired consistency.

Sprinkle chopped parsley over the top and serve immediately while hot, plated or family-style in the skillet.