1- Preheat oven to 350ºf, line a 9x13 inch pan with aluminum foil/parchment paper then spray with non-stick cooking spray, set aside.
2-In a large mixing bowl, whisk together the flour, cornstarch, sugar and, salt.
3-Cut the butter into small pieces and add dry ingredients. Cut the butter into mixture until crumbly and starts to come together.
4-Scoop mixture into baking pan and press it down into one even layer then bake at 350ºf for 20-25 minutes or until top is set then set aside while making filling.
1-In a large mixing bowl, whisk together the granulated sugar and flour. Add in eggs and lemon juice an dmix until fully combined pour the lemon filling over the warm crust and return to oven.
2- Bake for 18-22 minutes or until lemon filling is set and no longer jiggles.
3- Remove from oven and transfer to a wire wrack to cool completely for 1-2 hours, then cover tightly and refrigerate for at least 2 hours. Shift powdered sugar on top, slice into bars and enjoy.