Original Ingredients 3 cups all-purpose flour divided 2 1/2 cups for crust and 1/2 cup for filling 2/3 cups powdered sugar for the shortbread, plus more for dusting 1/2 tsp salt 12 tbsp unsalted butter melted 3 tbsp lemon zest, zest of three lemons 3 cups sugar 8 eggs large, room temperature 1 cup lemon juice fresh Instructions Heat oven to 350F and line a 9x13 baking dish with parchment paper.