The silky, flavorful base to this pasta makes it a garlicky blank slate for all kinds of endless variations. This is our slightly-adapted variant to use up what we had in the pantry; see the Notes below for the original recipe, plus a few more variations, as printed in Cook’s Science, by the Editors of Cook’s Illustrated and Guy Crosby. In testing, they noted minced garlic was best for its ability to toast evenly, and that a bit of raw garlic, added in addition to the gently-toasted bits, added some fresh garlicky zing; the amount of water to use, 2 quarts, is also crucial in creating the right amount of starchiness in the pasta water to help the sauce cling to the spaghetti without being oily.
The original recipe does not add capers, parsley, or almonds, but uses 1 cup chopped fresh basil and pine nuts instead, added in the same step (with the Parmesan).
Another delectable-sounding variation in the book omits the lemon zest, basil, and pine nuts, reduces the lemon juice to 1 tablespoon, then calls for 3 tablespoons capers, minced, 3 tablespoons currants, minced, and 2 anchovy fillets, rinsed, patted, dry, and minced, to be mixed into the pasta with the lemon juice.
Finally, for still another play on this pasta, omit the lemon zest, basil, and pine nuts, and reduce the lemon juice to 1 tablespoon. Stir 1 ½ teaspoons fennel seeds, coarsely ground, into the garlic-oil mixture with the red pepper flakes. Stir one 14-ounce can of artichoke hearts, chopped, into the pasta with the lemon juice. Add ½ cup hazelnuts, toasted, skinned, and chopped, into the pasta with the Parmesan, instead of the pine nuts.
Find it online: https://tworedbowls.com/2016/10/19/garlicky-spaghetti/