📋 Instructions

1. 1Heat the oven — Preheat the oven to 350°F (175°C) and line a 9x13-inch baking pan with parchment, leaving overhang on two sides. The overhang becomes your handles later.
2. 2Make the shortbread — Beat 1 cup (227g) butter with the powdered sugar and salt until creamy, about 2 minutes, then mix in 2 cups (250g) flour just until it forms a soft dough. You'll hear the mixer slow and the dough pull together.
3. 3Press and bake the crust — Press the dough evenly into the pan and bake at 350°F (175°C) for 18 to 20 minutes, until the edges are pale golden and the surface feels set when touched. Let it cool about 10 minutes while you make the filling.
4. 4Whisk the filling — Whisk the eggs, granulated sugar, remaining 2 tablespoons flour, lemon zest, and lemon juice in a bowl until smooth and slightly frothy. It should smell sharply of fresh lemon.
5. 5Pour over the warm crust — Pour the filling over the still-warm crust, spreading it evenly to the corners. Warm crust helps the filling grip and bake into one cohesive bar.
6. 6Bake the bars — Bake at 350°F (175°C) for 25 to 30 minutes, until the edges bubble gently and the center jiggles like set gelatin when you nudge the pan. It will smell sweet and citrusy, and the top should look matte, not wet.
7. 7Cool and chill — Cool completely on a rack, then refrigerate at least 1 hour to firm the curd. This is the step that gives you clean, sharp squares.
8. 8Slice and dust — Lift the slab out by the parchment, cut into 24 squares with a hot knife, and dust generously with powdered sugar just before serving. Taste as you go, then taste again.