01 -
Preheat oven to 175°C. Line a 20 cm x 20 cm baking dish with parchment paper or aluminium foil, leaving an overhang on the sides for easy removal. If using foil, grease lightly with non-stick spray.
02 -
In a stand mixer or large bowl with hand mixer, cream together cold cubed butter, vanilla extract, and 1 cup granulated sugar on medium-high speed until smooth, about 2–4 minutes.
03 -
Reduce mixer speed to low. Add flour in three additions, mixing until just incorporated after each addition to form a cohesive dough.
04 -
Transfer dough to the prepared baking dish. Press into an even layer covering the bottom. Bake for 25–30 minutes, or until edges are lightly golden and a toothpick inserted comes out clean.
05 -
While the base bakes, combine remaining 2 cups granulated sugar, eggs, lemon juice, and lemon zest in a stand mixer or large bowl. Whisk on medium speed until fully blended and slightly thickened, about 2–4 minutes.
06 -
Remove baking dish from oven. Evenly pour the lemon mixture over the hot shortbread base.
07 -
Return dish to oven and bake for an additional 25–30 minutes, or until the centre is just set and no longer jiggles when gently shaken.
08 -
Place baking dish on a wire rack and allow to cool completely in the pan for at least 30 minutes.
09 -
Dust bars with powdered sugar and additional lemon zest if desired. Use parchment or foil overhang to lift bars from pan, transfer to a work surface, peel away lining, and cut into 9 equal squares.