Clean and wash the carrots, leek and celery and cut them into small cubes. Peel onion and garlic. Finely dice onion, press garlic through a garlic press. Cut the bacon into strips, leave them crisp in a high frying pan and take them out.
Roast vegetables, onion and garlic in hot frying fat while turning, stir in tomato paste and deglaze with stock. Add tomatoes. Add bacon again and season the sauce with salt, pepper and oregano.
Bring to the boil and simmer covered for 15-20 minutes. In the meantime, cut olives into slices and add to the tomato sauce 5 minutes before the end of cooking time. Roast the pine nuts in a pan without fat, take them out immediately and let them cool down.
Prepare spaghetti in plenty of boiling salted water according to instructions on the packet. Drain and arrange on plates with olive and tomato sauce. Sprinkle with pine nuts and parmesan and serve.