Put the olive oil in a pan and fry the onion, finely chopped. Add the brandy. Allow to boil for a minute or two and add salt pepper and tomato paste. Add 2 liters of hot broth. Wash and dry the prawns broken into two parts three pasta (not very short). Add shrimp and pasta in broth. Allow to boil until it thickens slightly (to stay more spaghetti and shrimp and less water).