Bring a large pot of salted water to a boil, add the pasta and cook, stirring after 1 minute, until about three-quarters of the way done.
Meanwhile, heat the olive oil in a large saute pan over medium heat. Add the red pepper flakes and garlic and cook until just beginning to turn golden brown, then add the parsley. Add a ladle of the pasta water to stop the cooking process and allow the flavors to combine.
When the pasta is three-quarters of the way cooked, remove it from the water and add it to the saute pan. Add more pasta water as necessary to finish cooking the pasta, letting the liquid reduce as the pasta finishes to form a sauce.
Season with salt if desired and transfer to a large serving dish. Drizzle with more olive oil and serve.