Remove the tails and large claws from 20 boiled crayfish. Chop the tails and claws and fry with 1 spoon flour in 1 spoon crayfish butter. Add about 2 spoons sour cream, salt, and nutmeg, mix, and bring to a boil. When cool, beat in 2 egg yolks and heat. As soon as the mixture thickens, stuff puff pastry pirozhki shaped like books, and bake as above.