Meanwhile, in a large pot of boiling salted water, cook the pasta according to package directions. Drain the pasta, reserving 1 cup of the cooking water. Add the pasta to the skillet along with the reserved cooking water and the cheese and cook over moderately high heat, stirring, until the sauce is thick and creamy, 1 to 2 minutes. Transfer the pasta to a bowl, sprinkle with additional parmesan cheese and parsley and serve.