Beat butter and sugar together in a large bowl with an electric mixer until light and fluffy (approximately 2 - 3 minutes). Beat in the egg and the vanilla - scraping the bowl as needed.

Combine flour and salt in a separate bowl; add to butter mixture and mix to form a soft dough.

Place the dough on a lightly floured surface and knead until a ball forms.

Form the dough into 2 long rods and place on parchment or plastic wrap. Wrap and twist the ends to seal it completely. Drop the dough into the center of a paper towel roll and freeze for at least an hour.

Preheat oven to 350°F. Line two large baking sheets with parchment paper.

Once the dough is chilled, you can remove from the plastic wrap and roll in sprinkles or sanding sugar until completely coated.

Slice into 3/4" pieces and place on the prepared pans about 1-inch apart.

Bake for 10 - 14 minutes until the edges just begin to brown.

Allow to cool completely.

Serve and enjoy!