Fish is cleaned of skin and bones, place in boiling salted water and boil for about 10 minutes. Then drain the broth and put in the middle of the pan greased with butter. About fish rank diced potatoes. Beat the egg yolks with the cream, remaining butter, flour, grated cheese, diluted with strained fish broth and seasoned with pepper and salt to taste. With so prepared sauce pour the fish and potatoes. Bake 15-20 minutes in a moderate oven.