In a bowl of a stand mixer with a paddle attachment, beat together the butter, sugar, and salt until light and fluffy, about 2 minutes. Scrape down the bowl and beat again if needed to ensure the mixture is evenly mixed.
Add in the egg yolk, vanilla, and orange zest. Add the flour and mix until just combined.
Transfer the dough to a work surface, and roll the dough into a 12 to 15 inch long log. Sprinkle the dough with sparkling sugar and gently press to adhere. Wrap the log of dough into plastic wrap and refrigerate for at least 2 hours.
Preheat the oven to 350 degrees. Line baking sheet with parchment paper. Slice the cookies into 1/3-1/2″ thick rounds. Place 2 inches apart on the cookie sheet. Bake for approximately 15 minute, rotating the pan around halfway through baking to ensure they bake evenly.
Remove from the oven and allow the cookies to cool completely on the pan. Repeat with remaining dough. Use two baking sheets and parchment to make this bake go faster, baking one tray at a time.