- Vegetable oil, for greasing
- 2 sticks unsalted butter, diced
- 2 cups all-purpose flour
- 1/4 cup packed light brown sugar
- 1/2 cup confectioner’s sugar, plus more for garnish
- 1/4 tsp salt
- 4 large eggs, plus 2 egg yolks
- 2 cups granulated sugar
- 1/3 cup all-purpose flour, sifted
- 1 tsp grated lemon zest
- 1 cup fresh lemon juice (from about 8 lemons)
- Make the crust: Position a rack in the middle of the oven and preheat to 350 degrees F.
- Grease a 9-by-13-inch pan with vegetable oil and line with foil, leaving a 2-inch overhang on all sides; grease the foil with oil.
- Pulse the butter, flour, both sugars and the salt in a food processor until the dough comes together, about 1 minute.
- Press evenly into the bottom and about 1/2 inch up the sides of the prepared pan, making sure there are no cracks.
- Bake until the crust is golden, about 25 minutes.
- Meanwhile, make the filling: Whisk the whole eggs and yolks, sugar and flour in a bowl until smooth.
- Whisk in the lemon zest and juice.
- Remove the crust from the oven and reduce the temperature to 300 degrees F.
- Pour the filling over the warm crust and return to the oven.
- Bake until the filling is just set, 30 to 35 minutes.
- Let the bars cool in the pan on a rack, then refrigerate until firm, at least 2 hours.
- Lift out of the pan using the foil and slice.
- Dust with confectioners’ sugar before serving