Boil water for the pasta. Since you will use the pasta water to help emulsify a sauce, you want a little less water than normal - to concentrate the starch. Use 8-10 C of water in a pot over high heat. While the water boils, heat the olive oil over low heat in a pan or pot large enough to toss the spaghetti in later. You will need room to jostle and stir the spaghetti to create the sauce at the end.
1/4 C Extra Virgin Olive Oil
When the water is boiling, add 3-4 tsp of table salt (or 1-1.5 Tbsp of kosher salt), reduce the heat to medium, and add your spaghetti.
Salt, 8 Oz. Spaghetti
Cook the spaghetti to about a minute before al dente (roughly 1 minute before the earliest time range on the package, which is usually 8-9 minutes).
While the spaghetti cooks, add the garlic and chili flakes, and (optional) anchovies, to the hot oil and cook over low heat. You want to heat the garlic to a light golden color, being careful not to burn it. There should be just the faintest bubble/sizzle in the garlic. 4-5 Cloves Garlic, 1/2 tsp Red Chili Flakes, 1-2 Anchovy Fillets
Once the spaghetti is cooked, pick it straight out of the water (with kitchen tongs or a large fork) and add it to the hot oil and garlic.
Add a splash of the pasta water (roughly 1/4 C) and stir the pasta pretty vigorously to help emulsify the pasta water and oil together.
Continue stirring and flipping the pasta, mixing the pasta water and oil together, for 1-2 minutes until a sauce forms and thickens. If the pasta seems a little dry, add a few more tsp of pasta water as necessary and continue stirring for another minute.Note: this will be a very light sauce, and it will still generally be olive oil forward. Don't expect a perfect emulsification. Once the sauce is where you want it, cut the heat and mix in the parsley and (optional) lemon zest and juice to taste.
2-3 Heavy Pinches Chopped Flatleaf Parsley, 1/2 Lemon Zest and Juice
Taste for salt and red pepper and enjoy!