Preheat the oven to 180°C/350°F/gas ,

Plunge the crab or lobster into boiling water and boil for 15 minutes, then remove. Once cooled, remove all the meat from the shell, flaking it up into small pieces, and removing any splinters.,

To make the sauce, pound up the shells using a rolling pin and finely chop the garlic and chilli. Drizzle 1 tablespoon of olive oil into a saucepan over a medium heat and fry the garlic and chilli with the empty shell and legs.,

Add the tomatoes, breaking them up with a wooden spoon, and a large glass of water and simmer for 1 hour. Pass through a sieve, discarding the shells and season to perfection with sea salt and black pepper.,

Cook the spaghetti in boiling salted water according to the packet instructions until al dente then drain.,

Melt the butter and 1 tablespoon of oil in a large pan over a medium heat. Finely slice the garlic and chilli, then add them to the pan and gently fry.,

Scrub and debeard the mussels and slice the squid. Turn up the heat, add the mussels and prawns and cook for 2 minutes. Remove from the heat, discarding any unopened mussels.,

Add the tomato sauce, cooked pasta and crab or lobster meat. Pick the parsley and marjoram leaves and finely chop, then add them to the pan and mix everything together.,

Fold a 60cm x 120cm piece of greaseproof in half to get a crease and open it out again on a baking tray. Place the seafood mixture in the centre of one half.,

Beat the egg, then use it to brush all the edges. Bring the two sides together and seal well. Cook for 10 minutes, or until puffed up.