Cook the noodles al dente. Peel and dice the onions and garlic. Drain the mozzarella and dice it too.
Fry the onions in the pot (I like it when they are still a little crunchy - but everyone has to know that for themselves). Then add the can with the tomato puree. Let simmer for 2 - 3 minutes. Then add the tomato paste, vegetable stock, Italian seasoning, sugar and salt and pepper. Bring this to the boil briefly. Then add the clove of garlic. Finally add the mozzarella and wait for it to melt.
Put the pasta in a plate and pour the sauce over it. Garnish with parsley.