Bring a large pot of salted water to a boil. Cook the pasta according to package instructions until al dente. Drain and set aside, reserving some pasta water for adjusting the sauce consistency later, if needed.

In a large skillet over medium-high heat, add the sliced smoked sausage. Cook until the sausage is nicely browned on both sides, about 5-7 minutes. Remove the sausage from the skillet and set aside.

In the same skillet, reduce the heat to medium and add the butter. Once melted, add the minced garlic and sauté for about 1 minute, or until fragrant.

Pour in the heavy cream and bring to a simmer. Add the Cajun seasoning, starting with 1 tablespoon and adjusting according to your taste preference.

Gradually whisk in the grated Parmesan cheese until the sauce is smooth and creamy. If the sauce is too thick, you can thin it with a little reserved pasta water.

Add the cooked pasta and browned sausage to the skillet with the Cajun Alfredo sauce. Toss everything together until the pasta and sausage are well coated in the sauce. Season with salt and pepper to taste.

Serve the Smoked Sausage Cajun Alfredo hot, garnished with chopped parsley and optional red pepper flakes for an extra kick.