01 - Preheat the oven to 350°F. Line a 9x13-inch baking pan with parchment paper, leaving an overhang on the sides for easy removal.
02 - In a medium bowl, combine the melted butter, granulated sugar, all-purpose flour, and salt. Stir until a soft dough forms. Press the mixture evenly into the bottom of the prepared pan.
03 - Bake the crust for 18 to 20 minutes, or until lightly golden across the surface. Remove from the oven but keep the crust in the pan.
04 - While the crust bakes, whisk together the granulated sugar and flour in a large bowl. Add the eggs, freshly squeezed lemon juice, and lemon zest. Whisk until the mixture is completely smooth and well combined.
05 - Pour the lemon filling evenly over the warm pre-baked crust. Return the pan to the oven and bake for 18 to 20 minutes, or until the center is set and only has a slight jiggle.
06 - Allow the bars to cool completely in the pan on a wire rack. Once fully cooled, lift the slab out using the parchment overhang, slice into 12 bars, and dust generously with powdered sugar before serving.