01 - Preheat oven to 350°F. Line two baking sheets with parchment paper.
02 - In a medium bowl, whisk together the gluten-free flour blend, baking soda, and salt. Set aside.
03 - In a large bowl, beat the softened butter, granulated sugar, and brown sugar using an electric mixer until light and creamy, about 2 minutes.
04 - Add the egg, lemon zest, lemon juice, and vanilla extract to the butter mixture. Beat until fully combined.
05 - Gradually mix the dry ingredients into the wet mixture until just incorporated. Do not overmix.
06 - Gently fold in the shredded coconut and white chocolate chips, if using, until evenly distributed.
07 - Scoop tablespoon-sized mounds of dough onto the prepared baking sheets, spacing them 2 inches apart.
08 - Bake for 10 to 12 minutes, or until the edges are golden and the centers are set.
09 - Allow the cookies to cool on the baking sheets for 5 minutes, then transfer to a wire rack to cool completely.