Salt, as needed
225 grams of pasta
2 cups cooked chickpeas, home-cooked or canned
1/4 cup extra-virgin olive oil, plus more for drizzling
2 garlic cloves, smashed and peeled
1/2 onion, diced
1 tablespoon finely chopped fresh rosemary leaves
Pinch of chilli flakes, plus more as needed
1 1/2 cups chickpea cooking liquid (from a homemade pot; do not use the liquid from the can), vegetable stock or water
3 cups fresh parsley leaves (from 1 large bunch)
2/3 cup grated Parmigiano-Reggiano, plus more for serving
1 tablespoon unsalted butter
Finely grated zest of 1/2 lemon
Ground black pepper to taste
Bring a large pot of heavily salted water to a boil. Add pasta and cook until it is just shy of al dente. (It should be slightly underdone to your taste because you’ll finish cooking it in the sauce.) Drain well.
While the pasta is cooking, prepare the chickpea sauce: Place chickpeas in a large bowl and use a potato masher or a fork to lightly mash them; they should be about half-crushed.
Heat oil in a frying pan over medium heat. Add garlic cloves and fry until they are golden brown, about 2 minutes. Stir in onions, rosemary, chilli flakes and a pinch of salt. Cook, stirring occasionally, until onions are soft, about 10 minutes. Then stir in chickpeas and the cooking liquid, stock or water. Bring to a simmer and cook gently until most of the liquid has evaporated about 5 minutes.
Stir in pasta and parsley and cook until the pasta has finished cooking and is coated in the sauce, 1 to 2 minutes. Quickly toss in cheese, butter, lemon zest, black pepper to taste and salt if needed. Drizzle with olive oil and shower with additional cheese before serving.