Arrange an oven rack in the middle position and preheat the oven to 350°F. Line a 13 x 9 x 2-inch pan with a parchment sling both directions in the pan.

In a medium bowl, whisk the flour, confectioners’ sugar and salt. Add the melted butter and mix with a spoon until no dry streaks remain. Dough should end up in large crumbles.

Spread the crumbled dough evenly in the prepared pan. Press the dough into the pan, smoothing any seams, making sure the dough has no cracks. For an even crust, take a glass with a flat bottom and press down on the dough all around the pan to smooth the surface.

Bake for 20-25 minutes, or until pale golden brown.

While the crust bakes, make the filling. In a large bowl, rub together the sugar and lemon zest with your fingertips until the zest is completely mixed in and fragrant and damp. Whisk in the ½ cup flour. Add the eggs and lemon juice and whisk until fully combined.

Remove the baked crust from the oven and pour the egg mixture into the hot crust. Return to the oven and bake for an additional 23-25 minutes, turning the pan halfway through baking, until the filling is set, barely jiggles when the pan is shaken, and is lightly browned at the edges.

Cool completely for at least an hour. Then chill in the refrigerator until cold before cutting. Cut into bars. Sift confectioners’ sugar evenly over the top just before serving.