Sift together the flour and salt into a large bowl.
Put the butter into the bowl of an electric mixer fitted with the paddle attachment, and beat on medium speed until fluffy and light, about 2 minutes.
Add the confectioners' sugar and vanilla, and mix until combined. Reduce the speed to low, and slowly add the flour and salt mixture to the butter and sugar mixture, mixing on low speed until the dough comes together and is smooth. Turn the dough out onto a sheet of plastic wrap.
Cut the dough into quarters, wrap each piece in plastic wrap, and chill in the refrigerator for 2 hours.
When you're ready to bake the cookies, preheat the oven to 350 degrees F. Line two 9 by 13-inch baking sheet with parchment paper.
Remove the dough from the refrigerator and let it soften slightly. Using a rolling pin dusted with flour, roll out one of the dough quarters, (keeping the others refrigerated until you need them), on a lightly floured work surface to 1/4- to 1/8-inch thickness.
Cut the cookies into the desired shapes, and then use a metal spatula to transfer the cookies to one of the prepared baking sheets, spacing about 1 1/2 inches apart.
Sprinkle the cookies with decorating sugar, if desired.
Repeat with the remaining dough.
Bake the cookies until they are light brown around the edges and on the bottom, 8 to 12 minutes. Cool briefly on the sheets, and use a metal spatula to transfer the cookies to a wire rack to cool completely.
