Cook the spaghetti in salted water until al dente.
Prepare the sauce during the cooking time. To do this, roughly chop 1 smaller tomato and the mozzarella and finely puree together with the basil in a tall vessel with a hand blender. Then add the remaining tomatoes, also roughly chopped up, and the garlic and puree again very briefly, only for a few seconds, must not become too runny, pieces are welcome. Season with salt and pepper and mix in a dash of olive oil.
Drain the pasta, mix immediately with the sauce, arrange on plates and enjoy sprinkled with parmesan.