Using a pastry cutter or a food processor blend together the butter, sugar, and flour.
Press evenly into the bottom of a greased and parchment paper lined 9X13 inch baking pan.
Bake for 20 to minutes at 350°F (325°F if you are using glass bakeware). The crust should be slightly brown at the top edges.
FILLING
Whisk together the sugar flour, eggs, zest, and lemon juice until the sugar is dissolved.
Allow the topping to sit for about 10 minutes. Then whisk together again well and pour over the baked crust base.
Bake at 350°F for about another 20- 25 minutes or until the top is slightly browned and the filling appears to be set. Cool completely. Dust with powdered sugar.