In a large pot, bring 4 quarts water and 1 tablespoon salt to boil. Add spaghetti and cook until al dente, about 9 to 10 minutes. Reserve 1 cup pasta water and drain well.
In a large Dutch oven or saucepan, heat oil over medium heat until shimmering. Add garlic and cook until garlic begins to turn golden, but not scorched, about 1 minute.
Stir in capers, anchovy fillets, olives, tomatoes, and crushed red pepper (I like 1 teaspoon). Heat to boiling, reduce heat, and simmer uncovered until slightly thickened, about 30-40 minutes.
Add the pasta to the pot with the sauce and toss until evenly coated. Thin with pasta water if needed. Serve with Parmesan cheese and garnish with fresh basil.
Notes
Spaghetti: This recipe calls for spaghetti, but it's certainly not the end-all, be-all of pastas for puttanesca. Other long, thin noodles like linguine or bucatini also works beautifully.
Capers:Capers are the little pickled blossoms of a French shrub. I highly recommend giving the briny beauties a shot, especially in this salty and savory puttanesca sauce! I suggest 4 tablespoons capers for the 6-serving sauce. Scale up or down as you see fit.
Anchovy filets: While anchovies are easy to find in the tinned fish section these days, I seek out olive oil-packed anchovies in a little jar for easy storage. You can also opt for a generous squirt of anchovy paste instead; this is sold in toothpaste-like tubes at specialty grocery stores or online. One 1/4 teaspoon anchovy paste is equal to one anchovy filet.
Yield: This recipe makes six generous servings of a little more than 3 ounces of pasta (uncooked weight). I find this rich enough that this Spaghetti alla Puttanesca portion satisfies as a main dish, but multiply as desired.
Storage: Store leftovers covered in the refrigerator for up to 4 days.