Put the butter into a saucepan; when melted add the flour, and cook a few minutes, but not brown; add slowly the milk or cream, and stir until perfectly smooth. To this white sauce add the two yolks beaten, and stir them in off the fire; then add the meat, season, and replace on the fire until sufficiently thickened. Mix carefully with a wooden spoon, so as not to break the meat. The filling should be very creamy. The salpicon given below may be used for filling, if preferred.