This recipe is from Southern Living
2 1/4 cups all-purpose flour, divided
1/2 cup powdered sugar
1 cup cold butter, cut into pieces
4 large eggs
2 cups granulated sugar
1 teaspoon lemon zest
1/3 cup fresh lemon juice
1/2 teaspoon baking powder
Preheat oven to 350°F. Line bottom and sides of a 13- x 9-inch pan with parchment paper, allowing 2 to 3 inches to extend over sides; lightly grease.
Stir together 2 cups flour and 1/2 cup powdered sugar. Cut in butter using a pastry blender or fork until crumbly. Press mixture onto bottom of prepared pan.
Bake at 350° for 20-25 minutes or until lightly browned.
Meanwhile, whisk eggs in a large bowl until smooth; whisk in granulated sugar, lemon zest, and lemon juice.
In a separate small bowl, stir together baking powder and remaining 1/4 cup flour; whisk into egg mixture.
Pour mixture over hot baked crust.
Bake at 350°F for 25 minutes or until filling is set.
Let cool in pan on a wire rack 30 minutes.
Lift from pan, cool completely on a wire rack (about 30 minutes).
Cut into bars; sprinkle with powdered sugar.