Preheat oven to 350°
Spray or lightly grease a 13"x9" baking dish.
In a large mixing bowl, cream together butter and 1/2 cup powdered sugar.
Mix in flour. Mixture will resemble a fluffy cookie dough.
Press evenly into baking dish.
Bake for 20- 25 minutes or until edges and tops start lightly browning.
Set aside, crust does not have to cool completely before filling.
In a large mixing bowl, using a whisk, beat eggs.
Beat in juice and zest of both lemons.
Mix in sugar, flour and salt until thoroughly combined.
Pour filling into baked crust.
Bake at 350° for 20 - 25 minutes or until edges start to lightly brown and center is set.
Cool on wire rack.
To serve, cut into squares and dust with powdered sugar. Enjoy :)