To cook the crab, put it into a pan of cold salted water (the crab cooks more gently this way), add the bay leaf, and bring to the boil. Allow 20 minutes per spider crab, a little longer for a large regular crab.
Pick all the meat from the crab, cracking its legs, and keep the shell. There is very good brown meat in spider crabs: mix it all in with the white meat. Wash the shell.
To make the sauce, put the olive oil into a large pan on a low heat. Add the leeks and shallots and cook slowly until soft but not coloured – around 6–8 minutes. Add the bay leaf and pepper and continue cooking for a couple of minutes. Add the crabmeat and mix everything together, then pour in the brandy and wine and cook until the alcohol has evaporated. Finally add the tomato sauce and season with salt and pepper.
Spoon the crab mixture into the shells, and eat with a spoon, out of the shell.