Step 1

Make the Crust: Preheat oven to 350°F (177°C). Line a 9 X 13-inch baking dish with a double thickness of aluminum foil, allowing 2-3 inches to extend over long sides. Spray generously with nonstick cooking spray.

Step 2

Slice each stick of cold butter (1 cup) into about 8 slices. In the bowl of a food processor add flour (2 cups), powdered sugar (3/4 cup), and sliced butter. Pulse until butter pieces are about the size of peas. Pour mixture into prepared baking dish and press evenly into dish. Bake in preheated oven for 18-20 minutes until the edges of the crust begin to brown.

Step 3

Make the Filling: In a small bowl combine baking powder (1/2 teaspoon) and flour (1/4 cup) and set aside.

Step 4

In a large bowl, whisk the eggs (until smooth. Add sugar (2 cups), lemon zest (2 1/2 teaspoons), and lemon juice (1/3 cup), and combine. Add flour mixture and combine. Pour filling over hot crust and bake in preheated oven for 25 minutes or until filling is set. Cool bars in the pan set on top of a cooling rack for about half an hour. Remove bars from pan and cool on rack completely.

Step 5

Lift a generous layer of powdered sugar onto bars. Cut bars and serve.