Pre-heat oven to 350 degrees. Lightly spray a 13x9 inch baking pan (I used glass) with non-stick cooking spray. Line the pan with parchment paper allowing it to come up and over the sides. Lightly spray the parchment paper. Set aside.
In the bowl of a stand mixer combine the flour, sugar, salt and butter for the crust. Using the paddle attachment, mix on medium speed until it resembles coarse wet sand. Do not over-mix the crust or allow it to come together like dough.
Spread the mixture evenly into the prepared pan. Press firmly using the bottom of a glass to compress the crust. Place the unbaked crust in the freezer for 15 minutes.
Remove the crust from the freezer and bake until light golden brown, about 20 -25 minutes. Set aside. Reduce the oven temperature to 300 degrees.
While baking the crust, prepare the filling. In a large mixing bowl, whisk together the sugar, flour and cornstarch until combined. Add the strained fresh lemon juice and eggs. Whisk until well combined. Pour the filling over the warm baked crust and immediately bake at 300 degrees for 30 minutes or until the center does not juggle when tapped. Cool on a wire rack then refrigerate at least 2 hours before cutting.
If you are able, remove the lemon bars from the pan using the parchment to lift or slide the bars onto a cutting board. If needed you can cut them in the pan. Run a very sharp, thin knife under hot running water then carefully dry the blade. This will give you razor sharp cuts for a beautiful presentation. Repeat this process several times until all lemon bars are cut.
Adapted from a recipe by Amy Atlas, published in Sweet Designs via Oprah.Com