For Crust: Combine flour, sugar, butter, and salt until well mixed.
Press into an 8 inch square baking pan.
Bake at 350°F for 15 to 20 minutes until edges turn golden brown. Remove from oven.
For Filling: Combine beaten eggs, sugar, flour, and lemonade concentrate until well blended and pour over baked crust.
Return to oven and bake an additional 20 to 25 minutes or until filling is set.
While hot, dust top with sifted powdered sugar.
Place on wire rack and cool before cutting into squares.
Try not to polish off the whole pan in one sitting.