Fill a large pot with water, cover it, and bring it to a boil over high heat.

Set a large skillet on the stove over medium-high heat and add 2 tablespoons of the olive oil.

Put the drained chickpeas into the skillet in a mostly even layer.

Cook the chickpeas for 6 to 8 minutes, stirring every minute or two, until they look drier, a little crisp, and browned in spots.

Sprinkle the chickpeas with a pinch of the salt and 1/4 teaspoon of the red pepper flakes. Transfer them to a plate so they stay crisp.

When the water reaches a full boil, add the remaining 1 1/2 teaspoons salt to the pot.

Add the spaghetti to the boiling water and stir for the first 30 seconds so it does not stick together. Cook until the pasta is just tender, following the package time as a guide.

While the pasta cooks, return the skillet to medium heat and add the remaining 2 tablespoons olive oil.

Add the sliced garlic and the remaining 1/4 teaspoon red pepper flakes to the skillet. Cook for 30 to 60 seconds, stirring often, until the garlic smells fragrant and turns pale gold at the edges.

Scoop 1 cup of the pasta cooking water into a mug or heatproof measuring cup and set it near the stove.

Pour 1/2 cup of the pasta water into the skillet with the garlic. Let it bubble for about 15 seconds.

Stir the lemon zest and 1 tablespoon of the lemon juice into the skillet, then lower the heat to low.