Bring a large pot of salted water to a boil over high heat. Cook the pasta until it is al dente according to package instructions.
In a large skillet over medium-low heat, add the oil, garlic, chili flakes, and a pinch of salt and bring the garlic to a sizzle. Shaking the skillet occasionally, cooking for 3 minutes, until the garlic just until it turns golden. Turn off the heat if the pasta is still cooking.
When the pasta is done, drain it, reserving a bit of the pasta water. Reheat the garlic and oil mixture briefly if necessary.
Dress the pasta with the olive oil garlic sauce, adding a little more oil or some of the cooking water if it seems dry. Adjust the seasoning if needed, then toss with parsley and sprinkle with fresh parmesan cheese. (if using)