Preheat your oven to 350 degrees Fahrenheit. Cream together 1 stick of butter and 1/4 cup granulated sugar until well combined. Slowly add 1 cup of all-purpose flour and a pinch of kosher salt. Mix well until all ingredients are well incorporated. Press this mixture into a greased 8 x 8 pan. Refrigerate the pan for 30 minutes for the dough to set. Bake for 15 minutes or until lightly golden. Remove the crust from the oven and cool on a wire rack until cool to the touch. In the meantime combine the ingredients for your lemon filling. Using a whisk combine 3 eggs, 1/2 cup granulated sugar, the zest of 2 lemons, 1/2 cup freshly squeezed lemon juice, and 1/2 a cup of flour. Pour the lemon filling on top of the cooled crust and bake at 350 for approximately 35 minutes or until the filling is set. Once cooled, sprinkle with powdered sugar. Cut into large squares. The can be kept wrapped in your fridge for up to 3 days.