Preheat your oven to 350°F (175°C). Line an 8x8-inch baking pan with parchment paper, leaving an overhang for easy bar removal.

In a medium bowl, whisk flour, powdered sugar, and salt. Add cold butter cubes and, using a pastry cutter or your fingertips, blend until the mix resembles coarse crumbs. (Tip: Chill the bowl for 5 minutes if your kitchen’s warm.)

Press the crumb mixture firmly into the pan, covering evenly. A flat-bottomed glass or measuring cup helps create a smooth surface. Bake 18–20 minutes, until edges turn light golden.

While the crust bakes, whisk granulated sugar and flour together in a bowl. Crack in eggs, then whisk until pale and slightly thick. Stir in lemon zest, juice, and salt.

Carefully pour the filling over the hot crust. Return to the oven and bake 20–22 minutes, until the center sets but still jiggles slightly. Overbaking can make the filling chalky.

Let the bars cool on a wire rack for 15 minutes, then refrigerate at least 1 hour. Chilling sharpens the tangy lemon flavor and firms the bars for cleaner slices.

Lift the bars out using parchment overhang. Dust with extra powdered sugar (optional) and slice into 16 or 20 squares, wiping your knife between cuts for neat edges.

Serve chilled or at room temperature, alongside fresh berries or a dollop of whipped cream.