Ingredients:

  • 1 ½ cups All-Purpose Flour (for crust)
  • ½ cup Granulated Sugar (for crust)
  • ¼ tsp Salt (for crust)
  • 1 cup (2 sticks) Unsalted Butter, cold and cubed (for crust)
  • 2 cups Granulated Sugar (for filling)
  • ¼ cup All-Purpose Flour (for filling)
  • 4 Large Eggs, room temperature
  • ½ cup Fresh Lemon Juice
  • 2 Tbsp Lemon Zest
  • ½ cup Powdered Sugar (for dusting)

Instructions:

  1. Preheat oven to 350°F (175°C). Line a 9x13 inch (23x33 cm) metal baking pan with parchment paper, ensuring an overhang on two sides to create 'slings' for easy removal.
  2. For the crust: Combine flour, ½ cup sugar, and salt in a medium bowl. Cut in the cold, cubed butter until the mixture resembles coarse sand.
  3. Press the shortbread mixture firmly and evenly into the bottom of the prepared pan.
  4. Blind Bake: Bake the crust for 18–20 minutes, until the edges are just starting to turn pale gold. Remove from the oven, but keep the oven running.
  5. For the filling: In a clean bowl, whisk together the 2 cups of sugar and ¼ cup of flour until smooth. Incorporate the 4 eggs, whisking gently until just combined.
  6. Gently whisk in the fresh lemon juice and lemon zest until the filling mixture is uniform. Do not over-whisk.
  7. Crucial Step: Carefully and slowly pour the liquid filling over the hot, pre-baked crust. Return the pan to the 350°F (175°C) oven.
  8. Bake for 20–25 minutes. The filling should be mostly set around the edges but still have a slight, gentle wobble in the very centre when lightly shaken.
  9. Remove from the oven and allow to cool completely at room temperature (about 1 hour).
  10. Chill the bars in the refrigerator for a minimum of 3 hours, or preferably overnight, to allow the filling to set fully.
  11. Lift the chilled bars out of the pan using the parchment overhang. Cut into 16 squares and dust liberally with powdered sugar just before serving.