Preheat oven to 350° F. Prepare 2 baking sheets by lining with silicon mat or parchment paper.
In a medium bowl or stand mixer, combine melted butter, brown sugar and white sugar and stir until just combined. Add egg, egg yolk, and vanilla extract and stir until combined.
Add gluten free flour, baking soda, and salt and stir until combined. Gently fold in chocolate chips until mixed throughout.
If using a 1 oz. cookie scoop (about 2 Tbs of cookie dough): place on cookie sheet, about 2 inches apart. Bake for 10-12 minutes or until slightly golden brown. Remove from oven and cool for 2-3 minutes before transferring to a cooling rack. Yield about 34 cookies.
If using a 2 oz. cookie scoop (about 4 Tbs of cookie dough): place on cookie sheet, about 2 inches apart. Bake for 12-14 minutes or until slightly golden brown. Remove from oven and cool for 2-3 minutes before transferring to a cooling rack. Yield about 17 cookies.
After cookies have cooled completely, store in air-tight container. Best eaten day of baking or day after.