Bring a large pot of salted water to a boil. Cook the pasta until just al dente according to package directions, reserve 1/2 cup pasta water, and drain.

Heat olive oil in a large skillet over medium-high heat. Brown the sliced sausage for 3–5 minutes, turning occasionally, then transfer it to a plate if the skillet is crowded.

Cook the diced onion and red bell pepper for 4–6 minutes, until softened. Stir in the garlic and Cajun seasoning and cook for about 30 seconds.

Pour in the chicken broth and scrape up the browned bits from the skillet. Simmer for 2–3 minutes.

Add the heavy cream and bring the sauce to a gentle simmer. Cook for 3–5 minutes, stirring occasionally, until slightly thickened; do not let it boil hard.

Return the sausage to the skillet and add the drained pasta and Parmesan. Toss over low heat or off the heat until coated, adding reserved pasta water one tablespoon at a time if needed.

Taste before adding salt, then finish with black pepper and parsley. Serve hot.