1. Remove the stem from the tomatoes and make a cross incision on the bottom.
2. Immerse them for a few seconds in boiling water, then chill in water and ice.
3. Peel them and remove the seeds. Set aside.
4. Peel and finely slice the onion and gently brown it in a pan with the extra virgin olive oil. Add the tomatoes and season with a pinch of salt, black pepper and sugar if desired.
5. Cook gently for 15 minutes, then take off the heat, add the basil leaves and set aside.
6. Boil the spaghetti in plenty of boiling salted water. We recommend using 1 litre of water for every 100g of pasta.
7. Drain the pasta al dente, toss in the pan with the tomato sauce. Add a little of the cooking water, sprinkle with grated Parmigiano and serve.