Preheat oven to 350 degrees F. Line two baking sheeting with parchment paper or silicone baking mats.
Beat the butter and sugar on medium speed until combined and fluffy, 1 to 2 minutes.
Add the salt, vanilla and egg, and beat until combined, about 1 minute.
Reduce the speed to low and gradually add the flour until mostly combined.
Give a final few stirs with a rubber spatula to ensure the flour is totally incorporated (the dough will be thick).
Transfer the dough to a decorating bag fitted with a large open star tip.
Pipe the dough into 2-inch circles on the parchment paper or silicone baking mats.
Sprinkle with sugar.
Bake, one pan at a time, until light golden brown, 15 to 17 minutes.
Allow to cool completely before storing or serving.
