Wash, quarter, core and dice the tomatoes. Dice the sheep cheese as well. Finely chop the onions. Cut the garlic into thin slices and the basil leaves into fine strips. If necessary, pit the olives.
Heat oil in a large pan. Fry the onions and garlic in it. Add the tomatoes with the black and green olives and stir-fry for about 6 minutes. Mix in the sheep`s cheese and basil and stew for another 3 minutes. Season to taste with salt and pepper.
Cook the spaghetti al dente and serve with the sauce.