Preheat oven to 350°F. Grease a 9x13 inch pan
Crust: In a medium bowl, stir together flour, confectioners' sugar, and melted butter. Press into the bottom of the prepared pan.
Bake the crust in preheated oven for 15 minutes, or until golden.
In a large bowl, beat eggs until light.
In a separate bowl, combine sugar, baking powder, and remaining flour.
Add the sugar mixture to the eggs in parts. Stir until smooth
Stir in the lemon juice and zest. Pour the filling over the prepared crust and return to oven.
Bake for 40 minutes or until bars are set. Allow to cool completely before dusting the tops with confectioners' sugar and serving.