Preheat the oven to 350F. Line 2 baking sheets with parchment paper or a silicone baking mat.
Cream together the butter and sugar. Add the egg and mix until smooth.
Add the vanilla extract, salt, baking powder, baking soda, xanthan gum, and gluten-free flour and mix until combined.
Scoop the dough using a 1 ½ tablespoon cookie scoop, roll in additional sugar or colored sanding sugar, and place on the prepared baking sheet. You may also sprinkle each cookie with a little sugar instead of dipping or rolling each cookie dough ball.
Bake for 8-10 minutes.
