Bring a large pot of water, for the pasta, to a boil over medium heat, though you don't need to get started on the sauce until the water is pretty well boiling.
Pour the oil into a wide, shallowish frying pan, Dutch oven, or wok, and put it over medium heat.
Add the anchovies and cook for about 3 minutes, pressing and pushing with a wooden spoon, until the anchovies have almost "melted". Add the garlic and red pepper flakes or jalapenos and cook, stirring, for another minute.
This is probably the stage at which you will want to salt the boiling water and adding the spaghetti to cook, following the package instructions.
Going back to the sauce, add the tomatoes, olives, and capers to the pot with the anchovies and cook for about 10 minutes, stirring every now and again, by which time it will have thickened slightly. Taste for seasoning.
Just before the pasta is ready, remove and reserve about an espresso cupful of cooking water.
When the pasta is cooked as desired, drain and add the spaghetti to the tomato sauce, adding a little reserved pasta water, if needed, to help amalgamate the sauce. Scatter with chopped parsley, if there's some to hand, and serve in slatternly style, preferably with an unfiltered cigarette clamped between crimson-painted lips.
Make Ahead Note:
The sauce can be made 2 days ahead. Transfer the sauce to a nonmetallic bowl to cool, then cover and refrigerate as soon as possible. Reheat gently in large saucepan, frying pan, or wok, stirring occasionally, until piping hot.
The cooled sauce can be frozen in a resealable container for up to 3 months. Thaw overnight in the refrigerator and reheat as above.
NotesWell, how could I resist this translation of pasta alla puttanesca, whore's pasta as it usually is described in English? The general consensus seems to be that this is the sort of dish cooked by slatterns who don't go to market to get their ingredients fresh, but are happy to use stuff out of jars and cans. I hold my hands up to that. Or maybe one should just attribute the name gamely to the fiery tang and robust saltiness of the dish? But, anyhow, what better recipe to start off this section devoted to the fruits of the larder.
Please fire up the sauce if you want, but do know that even though the first mouthful might seem not quite hot enough, the heat builds as you eat. I sometimes go a little cross-cultural in my chili-case and use hot pickled jalapenos from a jar found on the Tex-Mex shelves of the supermarket. And while you're there, do look out for the tiny French nonpareil (or nonpareilles) capers: they may be smaller, but they pack more of a pungent punch than the larger capers.