1. Bring a large pot of salted water to a boil. Add the pasta and cook until al dente according to the package directions. Reserve 1 cup of pasta water, then drain the pasta.

2. Heat the olive oil in a large skillet over medium-high heat. Add the sliced chicken or turkey sausage with 2 teaspoons of Cajun seasoning. Cook for about 5 minutes, turning occasionally, until browned. Transfer the sausage to a plate.

3. Reduce the heat to medium. Add the onion, bell peppers, remaining Cajun seasoning, and red pepper flakes if using. Cook for about 3 minutes, until the vegetables begin to soften. Stir in the garlic and cook for 1 minute.

4. Whisk in the chicken broth, heavy cream, and tomato paste until smooth. Bring to a gentle simmer, then cook for 5 to 7 minutes, until slightly thickened.

5. Stir in the Parmesan cheese. Add the cooked pasta and browned sausage back to the skillet, tossing until everything is coated in the creamy sauce. Add a splash of reserved pasta water as needed to loosen the sauce.

6. Serve warm with extra Parmesan cheese and fresh parsley.