Tourta Athineiki (Orange-Walnut Cake, Athens Style)

    1/2 lb Butter; sweet                       1 ts Baking powder
      2 c  Granulated sugar                  1/4 ts Salt
      4    Eggs                                1 c  Walnuts; coarsely chopped
      1    Orange,(juice & grated rind)             Confectioners' sugar (opt.)
      3 c  All-purpose flour

  Cream the butter until light and fluffy, then gradually add the sugar.
  Continuing to beat, add the eggs one at a time, beating well, on
  medium speed, after each addition.  Gradually add the orange juice
  and rind. Meanwhile, sift the flour with the baking powder and salt
  and gradually add to the batter.  Add the walnuts last, blend another
  minute on medium high speed, and pour into a greased and lightly
  floured 8-inch tube pan. Bake in a moderate oven (350 F) for 25 to 30
  minutes until the color is a light chestnut and the cake springs back
  to the touch. (Watch carefully because this cake bakes quickly.) Turn
  onto a wire rack, round side up. Dust with confectioners' sugar and
  cool thoroughly before slicing.