Boil a pan of salted water and add the spaghetti. Cook according to packet instructions.
Just before the spaghetti is ready heat the oil a a frying pan on medium heat. Add the garlic and chilli and fry for 1 minute. Add the spring onion and prawns and cook for a further minute. Add the tomatoes to heat through and add salt and pepper to taste.
Drain the spaghetti. Return it to the pan and add the prawn-tomato mixture and and juices. Add chopped parsley and toss together.
Mixed seafood works just as well. You can also use chopped fresh chilli instead of chilli flakes.