Fill and boil a kettle of water and get all your ingredients and equipment together. You need a large, shallow pan with a lid. Put the pasta into the pan. Quickly chop the tomatoes in half and throw them into the pan. Grate in the zest of both lemons and add the oil and salt. Add about 1 quart/1 liter of boiling water, put a lid on the pan, and bring back to a boil. Remove the lid and simmer on high heat for 6 minutes, using a pair of tongs to turn the pasta every 30 seconds or so as it cooks. Meanwhile, remove any tough stalks from the kale or spinach and coarsely tear the leaves. Once the pasta has had 6 minutes, add the kale and continue to cook for a further 2 minutes. Once almost all the water has evaporated, take the pan off the heat and tangle the pasta into four bowls. If you like, top with a little Parmesan.