Combine the zest and sugar, then mix well. Now add the orange sugar and butter to a food processor, or stand mixer.
Pulse until they are well combined. Add in the vanilla and egg. Pulse again to combine. Scrape down the edges. Then add in the flour with the salt on top. With a fork or spoon mix in the salt.
Then pulse again to combine the flour. Scrape the sides and pulse a few more times.
Remove the dough from the bowl and place it on parchment. Roll it into a log, then cover with the saran wrap.
Place the cookie dough in the fridge and let it chill for at least an hour or up to 1 week.
Preheat the oven to 375 degrees. Line 2 baking sheets with parchment paper.
Remove the cookie log and cut it into ½-inch pieces. Place 12 per baking sheet and place them in the oven. Bake for 10-14 minutes. You want the edges to be just slightly browned.
Carefully remove the pan from the oven and let the cookies cool for about 5 minutes before gently placing them on a cooling rack.
That is it! They are ready to be enjoyed and ready to go.