Process butter, 1/4 cup confectioners' sugar and 1 cup flour in food processor 10 seconds, or blend with pastry blender. Pat dough evenly into 9 inch round pie plate.
Bake 12 to 15 minutes, until golden.
Combine eggs, white sugar, lemon zest, lemon juice and 3 tablespoons flour and mix until smooth; pour mixture over hot crust.
Bake 15 to 20 minutes more, until firm.
Let cool completely in baking dish.
Sprinkle with confectioners' sugar and cut into 12 triangles.
