1Bring a large pot of lightly salted water to a boil. Add spaghetti and cook, stirring until the water returns to a boil, then cook until about 1 minute shy of al dente.
2Meanwhile, add olive oil, sliced or smashed garlic cloves, and rinsed anchovy fillets to a cold large skillet.
3Turn the heat to medium-high. Cook, stirring occasionally, until the anchovies dissolve and the garlic turns golden brown around the edges.
4Add red pepper flakes and the juice from one lemon. Stir to combine.
5Transfer the nearly cooked pasta directly from the pot to the skillet, reserving about 1/3 cup of pasta water.
6Add reserved pasta water to the skillet. Toss pasta in the sauce and cook for 1-2 minutes, until the pasta is fully cooked and the sauce is creamy.
7Remove from heat. Add butter and toss until melted and the sauce is emulsified.
8Add grated parmesan cheese and chopped parsley (or other fresh herbs) to taste. Toss to combine.
9Serve pasta topped with additional parmesan and toasted Italian panko breadcrumbs.