In a large bowl, beat the softened butter and powdered sugar together until light and fluffy. (about 2 minutes) This creates a delicate texture in the cookies.
Scrape down bowl and add the vanilla extract. Mix in the salt. Gradually add in the flour, mixing on low speed until just combined. The dough will be crumbly but should hold together when pressed. Avoid over-mixing to keep the cookies tender.
Roll the dough into a log shape and wrap in plastic wrap. Chill for at least 1 hour in the refrigerator. This step helps the cookies hold their shape when baking.
Preheat your oven to 325°F (165°C) and line a baking sheet with parchment paper.
Slice the chilled dough into ¼-inch thick rounds and place them on the baking sheet. Sprinkle tops with the sparkling sugar. Chill for 10 minutes. Bake for 15-18 minutes, or until the edges are just lightly golden.
Allow the cookies to cool on the baking sheet for a few minutes, then transfer to a wire rack. Once cool, store in an airtight container.
