Preheat oven to 350°F (175°C) and line a 9x13 inch baking pan with parchment paper, leaving an overhang on the sides for easy removal.

In a medium bowl, combine flour and sugar, then cut in the cold butter until the mixture forms coarse crumbs.

Press the crumb mixture evenly into the prepared baking pan.

Bake the crust for 15-20 minutes, or until lightly golden, then remove from the oven and set aside.

While the crust bakes, whisk together granulated sugar and flour in a large bowl.

Add eggs one at a time, whisking after each addition until fully incorporated.

Stir in the lemon juice and lemon zest until the mixture is smooth.

Pour the lemon filling over the warm, pre-baked crust.

Return the pan to the oven and bake for an additional 20-25 minutes, or until the filling is set and edges are lightly golden.

Let the lemon bars cool completely in the pan on a wire rack before refrigerating for at least 2 hours to firm up.

Once chilled and set, use the parchment paper overhang to lift the bars from the pan, then slice into squares and dust with powdered sugar, if desired, before serving.