Preheat the oven to 325º Fahrenheit. Line the bottom and sides of a 9x13-inch baking dish with parchment paper, leaving enough overhang on the sides to easily lift the bars out later. Set aside.

In a medium mixing bowl, combine the melted butter, sugar, and salt. Stir in the flour until the mixture forms a thick dough.

Press the dough evenly and firmly into the prepared baking dish, aim for a smooth, even layer. Use the back of a spoon or a flat-bottomed glass to press it tightly.

Bake the crust for 25-30 minutes, or until the edges are lightly golden. Remove it from the oven and, using a fork, poke holes across the surface of the warm crust. Make sure you do not poke all the way. Set aside while you prepare the filling.

Whisk the sugar and flour in a large mixing bowl until evenly combined. Add the eggs and whisk until smooth. Gradually stir in the lemon juice. Make sure the mixture is free of lumps.

Pour the lemon filling over the warm crust. Spread it evenly across the top. Return the pan to the oven and bake for 27-35 minutes, or until the filling is set. The center should no longer jiggle when lightly tapped.

Allow the lemon bars to cool completely at room temperature for about 2 hours. Once cooled, transfer the pan to the refrigerator and chill for another 1-2 hours to ensure the filling sets firmly.

Use the parchment paper overhang to carefully lift the bars out of the pan.

Dust the top with powdered sugar, then slice into squares or rectangles with a sharp knife. Serve chilled or at room temperature.