2 cups all-purpose flour (divided: 1 1/2 cups for crust, 1/2 cup for filling)
1/2 cup granulated sugar (for crust)
1 cup unsalted butter, softened
1/4 teaspoon salt
4 large eggs
1 1/2 cups granulated sugar (for filling)
2/3 cup fresh lemon juice (about 3–4 lemons)
1 tablespoon lemon zest
Powdered sugar for dusting
Instructions
Preheat your oven to 350°F (175°C). Line a 9×9 inch baking pan with parchment paper, leaving a slight overhang on the sides. This will make it much easier to lift the bars out once they are cooled.
In a medium bowl, cream together the softened butter, 1/2 cup of sugar, 1 1/2 cups of flour, and salt. Mix until the dough is smooth and well combined. Press the dough firmly into the bottom of your prepared baking pan in an even layer.
Place the crust in the preheated oven and bake for 18 to 20 minutes, or until the edges are just lightly golden brown. While the crust is baking, you can prepare the lemon filling.
In a large bowl, whisk the 4 eggs until light and fluffy. Gradually add the 1 1/2 cups of sugar, the remaining 1/2 cup of flour, the fresh lemon juice, and the lemon zest. Whisk everything together until the mixture is smooth and there are no flour lumps remaining.
Once the crust is done baking, remove it from the oven. While the crust is still hot, pour the lemon filling mixture over it. Return the pan to the oven and bake for another 20 to 25 minutes. The filling should be set and no longer jiggly in the center.
Remove the pan from the oven and let it cool completely on a wire rack at room temperature. Once cooled, refrigerate for at least 2 hours to help the filling firm up. Before serving, lift the bars out using the parchment paper, dust generously with powdered sugar, and slice into squares.