Preheat your oven to 350°F (175°C). Line a 9x13-inch baking pan with parchment paper, leaving a 2-inch overhang on two opposite sides for easy removal.

Make the crust by whisking together 1 3/4 cups flour and 1/2 cup powdered sugar in a large bowl. Cut in the cold butter using a pastry cutter or your fingers until the mixture resembles coarse crumbs and holds together when squeezed.

Press the crust mixture evenly into the bottom of the prepared pan, packing it firmly with your hands or the bottom of a measuring cup. Bake for 18-20 minutes until the edges are lightly golden.

While the crust bakes, whisk together the eggs and granulated sugar in a medium bowl until well combined and slightly thickened, about 1 minute.

Add the lemon juice, lemon zest, remaining 1/4 cup flour, salt, and baking powder to the egg mixture. Whisk until smooth and no flour streaks remain.

When the crust is done, reduce oven temperature to 325°F. Pour the lemon filling over the hot crust, spreading it gently to the edges if needed.

Return to the oven and bake for 22-25 minutes until the filling is set around the edges but still slightly jiggly in the center — it will firm up completely as it cools.

Let the bars cool completely in the pan on a wire rack, about 1 hour, then refrigerate for at least 2 hours before cutting. Use the parchment overhang to lift the slab onto a cutting board, then slice into 24 squares with a sharp knife, wiping it clean between cuts. Dust with powdered sugar just before serving.