Bring a large pot of generously salted water to a boil. Add the spaghetti and cook according to the package directions until al dente, about 9 to 11 minutes.

While the pasta cooks, heat the olive oil in a large skillet over medium heat. Add the minced garlic and red pepper flakes, sautéing until fragrant but not browned, about 1 minute.

Stir in the capers and chopped olives, cooking for another 2 minutes to release their briny flavors into the oil.

Pour in the crushed tomatoes and the flaked pilchards along with their sauce. Stir gently to combine, and bring the mixture to a gentle simmer for 5 to 7 minutes until the sauce has slightly thickened.

Drain the cooked pasta, reserving 1/4 cup of the starchy pasta water. Toss the hot spaghetti directly into the skillet with the puttanesca sauce, adding a splash of pasta water if the sauce needs loosening to coat the noodles.

Taste the sauce and season with salt and black pepper as needed, keeping in mind the capers and olives are naturally salty. Serve immediately in warm bowls, garnished with a generous sprinkle of freshly chopped parsley.