Preheat your oven to 350 degrees. Line a 9 x 13 inch baking pan with parchment paper or spray it with cooking spray and set aside. We like to use two pieces of parchment paper - one for the length and one for the width. If you cut the pieces long enough then you will be able to lift out the bars after they have finished cooling using the edges of the parchment paper.
In a large bowl whsik together the powdered sugar and the flour. Using two forks or a pastry cutter, cut in the cold butter. Cut in the butter just until it looks like a somewhat fine crumb.
Press the crust mixture into the prepared pan. Bake for 20 to 25 minutes or utnil the edges just begin to brown.
While the crust is baking, combine the lemon juice, lemon zest, sugar, flour, and eggs in a large bowl. Beat with a hand or stand mixer for two minutes.
After the crust is done prebaking, pour the lemon mixture over the hot crust. Return to the oven and bake for an additional 20 minutes.
Remove the bars from the oven and let them cool completely. Lift them out of the pan using the edges of the parchment paper. Dust with powdered sugar, cut, and enjoy. See details in the post on storing and freezing.