Bring a large pot of salted water to a boil. Cook rigatoni according to package instructions until al dente. Reserve 1/2 cup of pasta water, then drain and set aside.
Prepare the Sausage:
Heat olive oil or butter in a large skillet over medium heat. Add the garlic sausage and cook until browned and cooked through. Remove and set aside.
Make the Alfredo Sauce:
In the same skillet, lower the heat and add minced garlic. Sauté until fragrant (about 30 seconds).
Pour in the heavy cream, stirring gently. Let it simmer for 2–3 minutes.
Gradually whisk in the Parmesan cheese until the sauce is smooth and creamy. Add nutmeg if using.
Season with salt and black pepper to taste.
Combine the Dish:
Return the sausage to the skillet and mix it into the sauce.
Add the cooked rigatoni to the skillet, tossing everything together until the pasta is coated with the sauce. If the sauce is too thick, add reserved pasta water, a little at a time, to reach your desired consistency.
Garnish and Serve:
Sprinkle with fresh parsley and extra Parmesan cheese. Serve immediately while hot and creamy.
