We have been experimenting with a few different Lemon Bar recipes and have deemed this recipe from The Hill Country Chef to be the BEST!
Preheat the oven to 350°F. Make the crust: Cut the butter into 1/2-inch pieces. In a food processor or using a hand-held pastry cutter, process all the shortbread ingredients until the mixture begins to form small pea-shaped lumps. Sprinkle the dough into a rectangular 13x9x2-inch baking pan. (The bars can also be made in a square 8- or 9-inch baking pan -- they will be thicker and take about 15 more minutes to bake.) Using your fingers or a metal spatula, press the dough firmly and evenly onto the bottom and 1/2 inch up the sides of the pan to form a 1/2-inch layer of shortbread. Prick all over with a fork. Bake the shortbread in the middle of the oven until golden, about 25 minutes. Remove it to a cooling rack. (Cover with foil to keep warm if necessary.) While the crust is baking, make the filling: In a large metal bowl, whisk the eggs and sugar together until well combined and a light yellow color. Stir in the lemon juice, flour, and zest. When the shortbread crust is ready and still hot, pour the lemon mixture evenly over it. Lower the oven temperature to 300°F. When it has reached the lower temperature, bake the bars in the middle of the oven until set, about 30 minutes. The top should be light brown and look a little bubbly and crusty. Let the bars cool completely in the pan on a cooling rack, then cut them into 3-inch squares with a nonserrated knife. Lightly sift confectioners' sugar over the cool bars before serving. If making these the night before a party, refrigerate them and reapply the confectioners' sugar just before serving. The sugar is absorbed as the lemon bars sit.