In a medium bowl, whisk together the gluten-free flour, baking soda, and salt. Set aside.
In a large bowl, whisk together the melted butter, brown sugar and granulated sugar. Whisk in the egg, egg yolk, and vanilla until combined.
Add the dry ingredients to the wet ingredients and mix with a rubber spatula to fully combine. Fold in the white chocolate chips and macadamia nuts.
Cover the dough and refrigerator for at least 2 hours and up to 4 days.
(If chilling for longer than 2 hours, allow to sit at room temperature for at least 20-30 minutes before rolling and baking.
Preheat the oven to 350F. Line baking sheets with parchment paper or silicone baking mats. Set aside.
Scoop and roll the cookie dough into balls. You can make smaller cookies with 1-1.5 tablespoons of dough, or bigger cookies with 2-3 tablespoons of dough per cookie. Roll the dough balls after scooping so they’re smooth.
Place a few inches apart on the baking sheet. (You can bake 12 small cookies or 6 large cookies at a time.)
Bake for 10-12 minutes or until lightly browned on the sides. The centers will look soft.
Remove from the oven and allow cookies to cool on the baking sheet for 5 minutes before transferring to a wire rack to cool completely. Enjoy!