Preheat oven to 350 degrees. Mix flour, powdered sugar and butter together until dough forms and press into a 9 x 13- inch pan coming up the sides about 1/2-inch.
Bake in preheated oven for 20 minutes. Remove from oven and pour filling over the crust. Make filling while crust bakes. To make filling, in a mixing bowl, beat 4 eggs with mixer while gradually adding 2 cups sugar. Add lemon juice and fold in flour and baking powder.
Pour over crust and bake for 25 minutes. Remove from oven and sprinkle with powdered sugar. Cool completely and then cut into finger sized bars or squares. Makes 24 pieces. Enjoy!