Cook the pasta in salted water according to the package directions until al dente. Drain the pasta, reserving ½ cup of the pasta cooking water. Set aside.

Heat the oil in a large skillet over medium-high heat. Add the garlic and red pepper flakes, cook, and stir for just a minute.

Carefully whisk the pasta water into the oil and garlic sauce on the stove until they are well mixed.

Add the cooked pasta to the sauce, stir, and cook for 3-5 minutes until the pasta has absorbed some of the liquid.

Remove from heat, season with salt, and pepper, and top with parmesan cheese, and parsley if desired.