Preheat your oven to 350°F (175°C). Grease your 9x13 inch baking pan with a little butter or line it with parchment paper for easy removal later.
In a mixing bowl, combine 1 cup of softened unsalted butter, 2 cups of all-purpose flour, 1 cup of powdered sugar, and ½ teaspoon of kosher salt. Mix until the ingredients are well incorporated and form a soft dough. Press this mixture evenly into the bottom of your prepared baking pan.
Place the crust in the preheated oven and bake for about 15-20 minutes, or until it’s lightly golden. Keep an eye on it, as you want a firm base for your lemon filling.
While the crust is baking, whisk together 6 large eggs and 3 cups of granulated sugar in a separate bowl until smooth. Add 4 tablespoons of grated lemon zest and 1 cup of fresh lemon juice to the egg mixture, whisking until everything is well combined. Finally, add 1 cup of all-purpose flour and mix until there are no lumps.
Once the crust is done baking, pour the lemon filling over the hot crust. Return the pan to the oven and bake for an additional 20-25 minutes, or until the filling is set and has a slight jiggle in the center.
Remove the lemon bars from the oven and let them cool in the pan on a cooling rack. Once completely cooled, dust the top with extra powdered sugar for a beautiful finish. Cut into squares and enjoy your Easy Lemon Bars!