Beat to a cream the butter with the sugar. Add the eggs, the yolks and whites beaten separately; then the flavoring. Stir in lightly enough flour to make a paste just firm enough to roll thin. Cut it into circles, and with a smaller cutter stamp out a small circle in the middle, leaving the jumbles in rings. Place them in a floured pan, brush the tops with white of egg, and sprinkle with pounded loaf sugar. The sugar should be in small lumps. Bake in a moderate oven to a light color.