01 - Preheat the oven to 350°F. Line two baking sheets with parchment paper.
02 - In a medium bowl, whisk together the gluten-free flour blend, baking powder, baking soda, salt, and poppy seeds until well combined.
03 - In a large bowl, cream the softened butter, granulated sugar, and lemon zest until light and fluffy, approximately 2-3 minutes.
04 - Beat in the egg, lemon juice, and vanilla extract until the mixture is smooth and thoroughly incorporated.
05 - Gradually add the dry ingredients to the wet mixture, mixing on low speed until a soft dough forms. Be careful not to overmix.
06 - Scoop tablespoon-sized portions of dough and roll them into smooth balls between your palms.
07 - Roll each dough ball in powdered sugar, ensuring an even and thorough coating for the crinkle effect.
08 - Place the coated dough balls 2 inches apart on the prepared baking sheets to allow for spreading during baking.
09 - Bake for 10-12 minutes, or until edges are set and tops display the characteristic crinkled appearance.
10 - Let cookies rest on the baking sheet for 5 minutes, then transfer to a wire rack to cool completely before serving.