Put into a saucepan one tablespoonful of butter; when it bubbles add one tablespoonful of flour; cook, but not brown; add one cupful of milk slowly, and stir until smooth; then remove it from the fire; add the salt, the pepper, the parsley, the yolks mashed fine, and lastly the lobster meat cut into pieces one half inch square. (Use a silver knife to cut lobster.) Be careful, in mixing, not to break the meat. Have the shell from which the meat was taken carefully washed and dried, leaving on the head; cut out neatly the inside shell of the tail-piece, and fit the two parts of the shell together. As the shell contracts in cooking, it is well to trim off a little from the sides of the body shell in order to leave an opening wide enough to admit a spoon in serving. Put the meat mixture into the shell. Cover the top with the bread crumbs, which have been moistened with one tablespoonful of butter. Place it in the oven for a few minutes to brown. If the meat of two lobsters is used, the shells of both may be used, or the two tail-shells may be fitted into one body shell, which will then hold all the meat.