Royal Highland Scottish Shortbread Cookies

2 cups all -purpose flour
1/4 tsp salt
1 cup unsalted butter (2 sticks), at room temperature, cut into small cubes 1/8-inch
3/4 cup powdered (confectioners) sugar
1 tsp vanilla extract

1.  In a mixer bowl of an electric mixer with  paddle attacked, add all dry ingredients, stir at low speed.  Add vanilla extract, stir to mix.  Add butter stir at medium speed until clumps is formed.  Do not overmix will make cookie tough. Shape the dough into 2 disks, wrap in plastic wrap and chill in the fridge for at least 1 hours or until firm, may stay overnight in the fridge.
2. Preheat oven to 350.  Line a rim baking sheet with parchment paper.  remove the dough from the fridge. Roll the dough into 1/4 to 1/2 -in thick  on a lightly flour surface. Then cut into round circles, rectangles or press the dough into a 8-in round ring then smooth the surface with a spoon then remove the ring and use a knife to score 16 wedges haft way to the thickness.  Put the baking tray in the fridge about 30 minutes.  Take it out and use a toothpick to poke the dough all over to help relieve steam if prefer. Bake until lightly golden about 8-10 minutes.

Note:
   Before baking, a layer of melted butter ( about 4 Tbs butter) may applied and sprinkle with vanilla sugar or cinnamon sugar( 1 cup sugar with 1 Tbs ground cinnamon) .
  After baking shortbread cookies can be dip into chocolate.
  The dough can be freeze well, thaw in the fridge before baking.