Prep the pan and oven: Preheat your oven to 350°F (175°C). Line a 9x13-inch pan with parchment paper, leaving a slight overhang for easy lifting. Lightly grease the sides if needed.

Make the crust: In a bowl, cream the softened butter and sugar until smooth and slightly fluffy. Add flour and salt. Stir until a crumbly dough forms. It should hold together when pressed.

Press and bake the crust: Press the dough evenly into the prepared pan, making sure the corners aren’t too thin. Prick the surface a few times with a fork. Bake for 18–20 minutes, or until lightly golden around the edges.

Whisk the filling: While the crust bakes, whisk sugar and flour in a bowl. Add eggs and whisk until smooth, but don’t beat too much air into it. Whisk in lemon juice, zest, and salt until combined.

Pour and bake again: Give the filling one last stir, then pour it over the hot crust. Return the pan to the oven and bake for 18–22 minutes. The center should be set and no longer jiggly, with tiny bubbles on top.

Cool completely: Let the bars cool in the pan on a rack until room temperature. For the cleanest slices, chill for 1–2 hours before cutting.

Dust and slice: Lift out using the parchment. Dust generously with powdered sugar. Use a sharp knife to cut into squares or rectangles. Wipe the knife between cuts for neat edges.