Boil the prawns in the same manner as described. When done, remove the meat from the claws and tails, pound the shells in a mortar with 2 ozs. of butter, and rub through a sieve. Melt the remaining 2 ozs. of butter in a saucepan, add the prawn butter, the flour, a little bread, previously soaked in milk, the chopped ham and prawn meat, dilute with a little of the prawn stock, stir in the cream, half the cheese, and season with salt, pepper and nutmeg. When the mixture thickens, put it in a fireproof dish, sprinkle with the remaining cheese, and bake in a moderate oven till lightly browned.