Place a large pot of water over high heat and bring up to a boil. Once boiling, add some salt and then the pasta. Cook to al dente according to package directions. Right before draining, remove and reserve 1 cup of the pasta cooking water.
Place a large skillet over medium-high heat, and add the EVOO. Add anchovies, garlic, and pepper flakes, if you're using them. Break up anchovies with a wooden spoon until they melt into the oil and garlic mixture.
Add reserved pasta water to the skillet, then the spaghetti, parsley, lots of pepper and a little salt to taste. Toss together and cook for 1 more minute so that the pasta has a chance to soak up some of the sauce. Serve with chunks of crusty bread for mopping up the excess goodness.