Cook the spaghetti in salted water until al dente. Rinse the squid tubes, pat dry and cut into rings. Wash and quarter the tomatoes. Peel and dice the garlic and onion and sauté with the chilli in 4 tablespoons of oil. Pour in the wine and simmer for 2 minutes. Take everything out of the pan.
Sauté the squid rings in the remaining oil for about 1 minute. Stir in tomatoes and wine and onion mixture. Let the whole thing simmer over low heat with the lid closed. Finally, season with salt and pepper and season to taste. Drain the spaghetti, collecting some of the cooking water. Fold the sauce and parsley into the spaghetti. Possibly add some cooking water and, if necessary, season again with salt and pepper. If you like, you can sprinkle parmesan on top.