Cromer crabs are wonderful this time of year but you can use any type of crab.  This recipe is Crab au gratin and is not difficult to produce.  Cook a large crab in a court-bouillon.  Let it cool.  When cold remove the claws and legs.  Then using the point of a knife, make an incision underneath the crab’s shell in such a way as to detach the upper part.  Remove the meat from claws and legs, and from the shell.  Cut the meat into large dice or mash it up with the help of two forks.  Put the meat in the hollow shell, which should be cleaned with hot water and covered on the bottom with a few tablespoons of Mornay sauce to which the crabs liver and the creamy parts are added finely pounded.  Cover with the same sauce.  Sprinkle with grated cheese, pour over some melted butter.  Brown in a moderate oven.