Bring a large pot of salted water to a boil and cook the pasta until al dente. Drain and set aside.
In a large skillet over medium heat, melt the butter. Add the sliced sausage and cook until browned.
Toss in the minced garlic and red pepper flakes. Cook until the garlic is fragrant, about 1 minute.
Pour in the cream and bring to a gentle simmer. Stir in the Parmesan cheese until the sauce thickens slightly.
Add the cooked pasta to the skillet and toss everything together until evenly coated.
Season with salt and pepper. Serve hot, garnished with fresh parsley.