Preheat the oven to 350°F (175°C).
In a medium bowl, whisk together gluten-free flour, baking powder, and salt.
In a large bowl, cream the softened butter and granulated sugar until light and fluffy.
Add the egg, lemon zest, and lemon juice to the butter mixture, and mix until smooth.
Gradually add the dry mixture to the wet ingredients, mixing until combined.
Chill the dough in the refrigerator for at least 30 minutes.
Scoop tablespoon-sized portions of dough and roll them in powdered sugar.
Place the cookie balls on a baking sheet lined with parchment paper, spacing them apart.
Bake for 10-12 minutes, or until the edges are just set.
Allow the cookies to cool on the baking sheet for 5 minutes before transferring to a wire rack.