Steam the cauliflower, prepared in the usual manner, until tender, separate into flowerets, and dispose each on a round of buttered toast; chop six mushroom caps and sauté five minutes in three tablespoonfuls of butter; add three tablespoonfuls of flour and, when blended with the butter, add gradually a cup and a half of white stock; stir until the boiling point is reached; after all the broth has been added let simmer ten minutes, then remove from the fire and stir in the yolks of three eggs, beaten and diluted with the juice of a lemon; season with salt and pepper and, if the heat of the sauce does not suffice to cook the egg, return to the fire over hot water for five minutes, stirring constantly meanwhile. Pour this over the flowerets of cauliflower on the toast, sprinkle with buttered crumbs and brown quickly in a very hot oven. If served on a large dish, garnish with mushrooms stuffed and baked. Served individually, omit the garnishing.