This recipe is adapted from The Joy of Baking. I've cut the amount of sugar in half so it makes this recipe super tart, just the way I like it. :)
1/2 cup unsalted butter, room temperature
1/4 cup confectioner's (powdered or icing) sugar
1 cup all purpose flour
1/8 teaspoon salt
1/2 cup granulated white sugar
2 large eggs
1/3 cup fresh lemon juice (approximately two large lemons)
Zest of 2 lemons
2 tablespoons all purpose flour
Preheat oven to 350F. Butter an 8 x 8 inch pan. I only have an 8 x 6 inch pan so my shortbread crust (my favourite part) is super thick.
Shortbread Crust: Beat the butter and sugar until light and fluffy. Add the flour and salt and beat until the dough just comes together. Press onto the bottom of your prepared pan and bake for about 20 minutes, or until lightly browned. Remove from oven and place on a wire rack to cool while you make the filling.
Lemon Filling: Beat the sugar and eggs until nice and smooth. Add the lemon juice and zest and stir to combine. Fold in the flour. Pour the filling over the shortbread crust and bake for about 20 minutes, or until the filling has set. Remove from oven and place on a wire rack to cool.
To serve: Cut into squares and dust with confectioner's suger (I usually don't do this because I find that the confectioner's sugar melts anyway and it just makes it more sweet). These are best eaten the day they are made but can be covered and stored in the refrigerator for a day or two.