Bring a large pot of salted water to a boil. Cook the pasta according to the package directions until al dente, keeping the noodles pleasantly firm in the center.

While the pasta cooks, finely chop the parsley and mince the garlic. For a smoother sauce, pulse the parsley and garlic together in a food processor.

Combine the parsley, garlic, olive oil, salt, and freshly ground black pepper in a bowl. Stir well so the seasonings are distributed throughout the oil.

Reserve about 1/2 cup of the pasta-cooking water before draining the pasta. Return the drained pasta to the warm pot.

Add the parsley-oil mixture to the warm pasta and toss thoroughly. Add the Parmesan after removing the pot from direct heat, then toss quickly so the cheese coats the noodles instead of clumping.

If the pasta seems dry or the cheese does not coat evenly, add the reserved pasta water one tablespoon at a time while tossing. Taste and adjust the salt and pepper, then serve immediately with additional Parmesan if desired.