Boil prunes until very soft; remove the stones. Mash well; add the yolks of 4 beaten eggs, 3 tablespoonfuls of sugar, 1 cup of bread-crumbs, 1 teaspoonful of vanilla, ½ cup of chopped nuts, and the whites of the eggs beaten stiff. Put in a well-buttered pudding-dish and bake in a moderate oven until done. Serve cold.