Heat oven to 350 degrees.
Mix 2 cups flour and 1/2 cup powdered sugar into medium sized bowl.
Use a pastry cutter to cut in cubed butter until the dough is crumbly.
Pat the dough into a 13x9 glass pan, pressing flat and into the corners.
Bake the crust at 350 degrees for 25 minutes. Remove and let cool.
Meanwhile, beat 4 eggs with a hand mixer until fluffy.
Gradually beat in the white sugar and lemon juice.
Sift in the remaining 1/4 cup of flour and the baking powder using a sifter.
Incorporate gently and then pour the mixture over the cooled crust.
Bake the lemon bars again at 350 degrees for 25 minutes or until the tops are slightly browned.
Once completely cooled, sift remaining powdered sugar over the top and cut in squares.