Preheat your oven to 350 degrees. Grease or line a 9x13 pan and set aside.
Cream the butter with the flour, sugar, and salt in the bowl of an electric mixer using the paddle attachment. This should take 2 to 3 minutes at medium speed.
Press into the bottom of your prepared pan. Bake for 20 minutes.
While the crust is cooling, whisk together the sugar, flour, eggs, lemon juice, and lemon zest.
Pour over the crust and bake and additional 20 minutes or until the custard is set.
Refrigerate until chilled, sprinkle with powdered sugar, and enjoy.