Sift flour and salt. Mix together in a bowl and set aside.
Mix butter on high speed until fluffy (approx. 3-5 min).
Gradually add confectioners' sugar to the butter and continue to mix until pale and fluffy.
Add flour and salt mixture to the butter and sugar until combined.
Butter a square pan. Then pat the shortbread into the pan so it is no more than ½ inch thick.
Refrigerate for at least 30 minutes.
Preheat oven to 300°F.
Cut into squares.
Bake until golden and make sure the middle is firm (approx. 45-60 minutes).
Cool completely and enjoy!
Notes
The original recipe calls for unsalted butter and 1/4t of salt. But I only ever buy salted butter, so the conversion was close enough.I used a Kitchenaid mixer, but a hand mixer would probably work as well.I cut mine into rectangles to be a little more authentic to the show!In my oven, the biscuits took 55 minutes to cook and I probably could have gone for the full 60 minutes.