Shortbread Cookies

Preheat oven to 325° and line a baking sheet with parchment paper. In a large bowl using a hand mixer, beat together butter and powdered sugar then add vanilla. Add flour and salt and beat until combined. If dough is still crumbly, press together with your hands into a cohesive dough.  Wrap in plastic wrap and refrigerate for 30 minutes.  On a floured surface, roll dough out into an 8"-x-8" square, about ½” thick.  Use a bench knife to guide edges of dough into a neat square shape.  Cut dough into 2” squares and place on prepared pan. Brush cookies with egg wash, then sprinkle cookies with coarse sugar and bake until lightly golden and set, 18 to 20 minutes.