Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.
In a medium bowl, whisk together the gluten-free flour, baking soda, and salt. Set aside.
In a large mixing bowl, cream together the softened butter, brown sugar, and granulated sugar until light and fluffy, about 2-3 minutes.
Beat in the egg and vanilla extract until well combined.
Gradually add the flour mixture to the butter mixture and mix until just combined. Fold in the white chocolate chips, crushed pretzels, and peppermint extract.
Drop balls of dough onto the prepared baking sheet, spacing them about 2 inches apart.
Bake for 10-12 minutes until the edges are lightly golden and the centers remain soft.
Allow the cookies to cool on the baking sheet for about 5 minutes before transferring them to a wire rack. Sprinkle with crushed candy canes.