Bring a pot of slightly salted water to the boil, score the tomatoes with two small cuts shaped like an X and scald them for 30 seconds. Take the tomatoes out with a skimmer if you want to use the water for your pasta, then cut them in half, remove the seeds and break them slightly with your hands.
In a large pan, brown three small cloves of garlic, with the peel on, in a little olive oil, then add the tomatoes and cook on a low heat for around 15 minutes.
Add a bunch of basil, washed and dried – tear it a little with your hands if you prefer. Cook the sauce for another few minutes and turn the heat off.
Purée the tomatoes and basil (remove the garlic cloves first) in a food mill or blender. Boil the spaghetti in salted water, drain when al dente and put back into the pan. Add the tomato sauce, mix and serve with olive oil, basil leaves and grated Parmesan.