Cook the pasta:

• Bring a large pot of salted water to a boil and cook the pasta according to package instructions. Drain and set aside.

Prepare the protein (optional):

• If using chicken, season both sides with salt, pepper, and Cajun seasoning. Heat 1 tablespoon of olive oil in a large skillet over medium-high heat. Cook the chicken for 5-7 minutes on each side, until golden and cooked through. Remove from the pan and slice it into thin strips. For shrimp, cook seasoned shrimp in the skillet for 2-3 minutes on each side until they turn pink, then remove them from the skillet.

Make the sauce:

• In the same skillet, melt the butter over medium heat. Add the diced onion and bell pepper and sauté for 3-4 minutes until softened.
• Add the garlic and cook for an additional 30 seconds until fragrant.
• Stir in the Cajun seasoning, smoked paprika, and cayenne pepper (if using), and cook for another minute.

Add the creamy sauce:

• Pour in the heavy cream and chicken broth, stirring to combine. Bring to a simmer and cook for 3-4 minutes until the sauce starts to thicken.
• Stir in the grated Parmesan cheese and cook for another 1-2 minutes until melted and the sauce is smooth. Taste and adjust seasoning with salt and pepper as needed.

Combine pasta and sauce:

• Add the cooked pasta to the skillet with the creamy sauce and toss to coat evenly. If the sauce seems too thick, add a bit more chicken broth or pasta water to thin it out.

Serve:

• Top with the cooked chicken or shrimp and garnish with fresh parsley.
• Serve immediately with extra Parmesan if desired.