1. Preheat the over to 350 degrees. Prepare a 9×9 pan with parchment paper
2. Ensure that there is excess parchment paper hanging over all four sides by at least 1 inch
3. Finely grate the zest of 1 lemon,  Add the zest to a mixer and set the lemon aside
4. Add 1/4 cup sugar and use your fingers to work the zest until fragrant
5. Add butter and salt and beat with a paddle on medium speed until creamy, about 2 minutes
6. Add the flour and beat until fine crumbs of dough form
7. Transfer to baking pan and press down evenly to cover the bottom of the pan.
8. Bake the crust until golden brown, about 15-20 minutes

To Make the Filling:

1. Crack the eggs into a medium bowl and whisk until beaten
2. Finely grate the zest from one lemon
3. Juice 5 lemons or until you have 3/4 cup of lemon juice
4. Add the lemon juice, 1 1/2 cups sugar, and 1/2 tsp salt into the bowl of eggs
5. Whisk until smooth. Sift 1/3 cup flour over mixture and whisk until smooth

When the crust is ready:

1. Pour the filling over hot crust
2. Bake until filling is set, about 18-20 minutes
3. Let cool for 1 hour, transfer to the refrigerator and chill for at least 3 hours
4. Lift out of baking sheet, dust with powdered sugar and cut into squares