Step 1

Bring 4 quarts of water to a rapid boil in a large pot. Add the spaghetti and 1 tablespoon salt; cook, stirring often, until the pasta is al dente. Reserve 1/3 cup of the cooking water, then drain the pasta.

Step 2

Meanwhile, in a 10-inch skillet, over low heat, add 3 tablespoons olive oil, two-thirds of the minced garlic, and 1/2 teaspoon salt. Cook, stirring constantly, until the garlic begins to foam and is sticky and has taken on a very pale light brown color, about 10 minutes. Remove the pan from the heat and add the remaining minced garlic, red pepper flakes, parsley, lemon juice, and 2 tablespoons of the reserved cooking water.

Step 3

Transfer the drained pasta to a warm serving bowl. Add garlic mixture, remaining 3 tablespoons of olive oil, and the rest of the reserved cooking water to the pasta; toss to combine. Season to taste with salt. Serve immediately, passing some Parmesan cheese separately.