Bring a 6-quart pot of water to a boil with 1 tbsp salt. Add the strascinati and cook according to the package until al dente. Reserve 1 cup of the pasta water, then drain.

Heat 3 tbsp olive oil in a 12-inch skillet over medium heat. Add the breadcrumbs in a single layer and toast for 4 to 5 minutes, stirring often, until deep golden brown.

Season the breadcrumbs with a pinch of salt, then tip them onto a plate and set aside.

Add the remaining 3 tbsp olive oil to the same skillet over low heat. Add the garlic, anchovy fillets, and chili flakes, stirring until the anchovies dissolve into the oil, about 2 to 3 minutes. Don't let the garlic brown, it turns bitter fast.

Add the drained pasta to the skillet along with a splash of the reserved pasta water. Toss over low heat for 1 to 2 minutes, adding more pasta water as needed, until the pasta looks glossy and coated.

Remove the skillet from the heat. Stir in half the toasted breadcrumbs and the chopped parsley.

Plate the pasta in shallow bowls. Top with the remaining breadcrumbs, lemon zest if using, and a crack of black pepper. Serve right away while the crumbs are still crisp.