Bring a large pot of salted water to a boil. Cook the penne pasta according to the package instructions until al dente. Drain and set aside.

Heat the olive oil in a large skillet over medium heat. Add the sliced smoked sausage and cook until browned, about 5 minutes. Remove the sausage from the skillet and set aside.

In the same skillet, add the diced onion and cook until softened, about 3 minutes. Add the minced garlic, red bell pepper, and yellow bell pepper, and cook for another 3-4 minutes until the vegetables are tender.

Stir in the Cajun seasoning, smoked paprika, and crushed red pepper flakes (if using). Cook for 1 minute to toast the spices.

Add the diced tomatoes, heavy cream, and chicken broth to the skillet. Stir well and bring the mixture to a simmer. Let it cook for 5 minutes, allowing the flavors to meld.

Reduce the heat to low and stir in the grated Parmesan cheese until melted and the sauce becomes creamy. Season with salt and black pepper to taste.

Return the cooked sausage to the skillet, followed by the cooked pasta. Toss everything together until the pasta is evenly coated in the sauce.

Remove the skillet from the heat and garnish with chopped fresh parsley. Serve immediately.