Peel and finely dice the onions. Dice the bacon finely as well. Pluck off 1 stalk of sage leaves, wash and cut into fine strips
Fry the onions and bacon in hot oil. Add canned tomatoes with juice and chop roughly. Season with salt, pepper and sage. Braise at medium heat for about 10 minutes. Put spaghetti in plenty of boiling salted water and cook for 8-10 minutes
Clean, wash, quarter and seed the tomatoes. Then dice finely and heat in the sauce, season to taste. Drain the spaghetti and serve with the sauce. Grate cheese over it. Garnish spaghetti with remaining sage