Cook the Pasta: Fill a large pot with salted water and bring to a rolling boil. Add penne pasta and cook until al dente, about 10-12 minutes. Drain pasta, reserving some pasta water.

Sauté the Chicken: Heat olive oil in a large skillet over medium-high heat. Season chicken breast with Cajun seasoning and add to the skillet. Cook for 4-5 minutes on each side until golden brown. Remove from skillet and keep warm.

Cook the Shrimp: In the same skillet, add more olive oil if necessary and cook shrimp for 2-3 minutes until pink and opaque. Set aside with the chicken.

Sauté the Sausage and Veggies: Add sliced andouille sausage to the skillet and sauté for about 2 minutes. Then add bell peppers, red onion, and minced garlic. Cook until vegetables are tender, about 4 minutes.

Create the Sauce: Pour in heavy cream, stirring to combine. Let it simmer for 2-3 minutes before adding melted Parmesan cheese. Adjust seasoning with salt and pepper.

Combine Everything: Return cooked chicken and shrimp to the skillet along with the drained pasta. Toss together gently for 1-2 minutes until pasta is well-coated with sauce.

Add Garnish and Serve: Sprinkle chopped parsley over the top. Serve immediately on individual plates or family-style.