Preheat the oven to 350 degrees. Line an 8 by 8 inch pan with parchment paper and spray with nonstick spray.
Add flour, powdered sugar, and cubed butter to the food processor and pulse together until crumbly. Pat the dough mixture evenly and firmly into the prepared pan. Don’t worry that the dough isn’t holding together just yet. It will bind as it bakes.
Bake for 20 minutes, or until light golden brown around the edges.
For the Filling
In a medium bowl, combine eggs, sugar, flour, baking powder, and lemon juice and beat together with a hand mixer on medium speed until smooth and creamy (about one minute).
Pour the lemon mixture over the cooked crust, and return to the oven for an additional 20-24 minutes.
To Finish
Allow the bars to cool completely, then dust with powdered sugar.