Mix and sift two cups flour and one-half cup brown sugar. Wash three-fourths cup butter and work into first mixture, using tips of fingers. Roll to one-third inch in thickness, shape with a fluted round cutter five inches in diameter. Cut each piece in quarters and crease with the dull edge of a case knife to represent folds of a fan. Brush over with yolk of egg diluted with three-fourths teaspoon water. Bake in a slow oven.