Sift flour and salt and set aside.
Using a paddle attachment, mix butter on HIGH for about 5 minutes, scraping at halfway point.
Add sugar . Continue to mix on HIGH for about 2 minutes until appearance is pale in color and fluffy. Scrape sides of bowl halfway.
Add flour mixture. Blend in on LOW speed until it begins to clump together and all flour is incorporated.
Line 8" x 8" pan (or a 1/4 sheet pan) with parchment paper.
Dump dough in center of pan and distribute it. Pat/press it gently to the outside edges of the pan. You can use a small roller or an offset spatula to help spread and level dough out.
Chill i n the fridge for at least 30 minutes.
Preheat oven to 300 °F.
Using a bench knife, or other tool, cut into 16 squares or 32 rectangles(my preference) in the 8" x 8" pan.
With a fork, pierce each section(rectangles) twice. This allows the heat to penetrate and bake the dough.
Bake until edges appear to be slightly golden brown. This will vary depending on the size of pan you choose to use. From my experience, about 65-70 minutes for an 8' x 8" pan and about 50-55 minutes for a quarter sheet pan.
Remove to a cooling rack and let it rest about 10-15 minutes. Use bench knife to recut sections scored before baking. Allow it to cool completely. Lift shortbread from pan using parchment paper.
Separate and store in a sealed container.
