From Retro Desserts by Wayne Harley Brachman, the book and this recipe are HIGHLY recommended.

For the Crust
Nonstick vegetable spray to coat pan
1 cup all-purpose flour
1/4 cup confectioners' sugar
1/2 cup (1 stick) unsalted butter at room temp

For the Filling
1 cup sugar
1/4 cup all purpose flour
4 large eggs
Zest and juice of 4 lemons (1/2 cup)
1/2 teaspoon vanilla extract
Confectioners' sugar for coating

Make the crust by lightly coating a 9 by 9 inch or 7 1/4 inch by 11 1/4 inch baking pan with nonstick vegetable spray.

In a mixing bowl or food processor, mix together the flour, sugar and butter until it just forms into a dough.  Lightly pat it over the bottom of the pan, making sure that it clings 1/4 inch up the sides.  With a form, prick little holes in the dough. Refrigerate at least 1 hour, until firm.

Preheat oven to 375 degrees F. Bake the crust for 15 minutes on a rack in the middle of the oven. It is done when lightly tanned and set.

While the crust is baking, make the filling by combining the sugar and flour in a medium bowl. Beat in the eggs, then the lemon zest, juice and vanilla.

Pour the filling over the finished crust and bake 15 minutes, until set. Set the pan on a rack to cool. When it is cold, lightly dust with confectioners' sugar. (If you do it when it isn't completely cold, the sugar will just melt and disappear.) Cut into 2 inch pieces.

Makes 12 bars.