Viennese jam pockets

1 1/4 c  Unsalted butter' softened
    2/3 c  Sugar
      2    Hard-cooked egg yolks
      1    Egg yolk; lightly beaten
      1 ts Grated orange peel
      2 ts vanilla extract
  3 1/4 c  Sifted all-purpose flour
  1 1/2 c  Thick jam; or preserves
      1 tb Water
      2    Egg whites
 
     Cream the butter and sugar together by beating them against the side of
  a bowl with a wooden spoon or by using an electric mixer at medium speed
  until the mixture is light and fluffy.
    Rub the hard-cooked egg yolks through a sieve with a wooden spoon, then
  stir them, the egg yolk, orange peel, vanilla and salt into the
  butter-sugar mixture.  Add the flour 1/2 cup at a time; stir until the
  mixture becomes a slightly stiff dough. Shape the dough into a ball, wrap
  it in wax paper or plastic wrap and refrigerate it for about an hour.
     On a lightly floured surface, roll the dough out into a 15- inch square
  about 1/8-inch thick. With a pastry wheel or sharp knife, cut the large
  square into 3-inch squares. Drop a teaspoon of jam onto the center of each
  square. Then lift a corner of each square and fold it over the opposite
  corner, forming a triangle. Seal the edges by pressing them firmly with the
  tines of a fork, then refrigerate them for 30 minutes.
     Preheat the oven to 350.  With a pastry brush or paper towel lightly
  butter two 14-by-17-inch baking sheets, sprinkle a handful of flour over
  the butter, and knock out the excess flour by striking the inverted sheet
  against the edge of a table. Arrange the chilled triangles on the baking
  sheets, leaving at least 1/2-inch of space between them. Gently prick the
  center of each triangle with a fork.
   Mix the water and the egg whites together by beating them lightly with a
  fork. Then, with a pastry brush, coat each triangle lightly with egg white
  mixture.   Bake the triangles on the middle shelf of the oven for 10 or 15
  minutes, or until they are lightly browned. Remove them from the baking
  sheets with a metal spatula and cool them on a cake rack before serving.
  Source:The Cooking of Vienna's Empire
 
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