Preheat your oven to 350°F. Line rimmed baking sheets with unbleached parchment paper and set them aside.

In a large bowl with a handheld mixer or the bowl of your stand mixer fitted with the paddle attachment, place the butter, granulated sugar, and light brown sugar. Beat on medium-high speed until light and fluffy (about 3 minutes).

Add the egg and vanilla, and beat until smooth (about 1 minute). Do not overmix.

Add the flour blend, xanthan gum, cornstarch, baking soda, salt, and chocolate chips. Using a large spoon or spatula, mix the dry ingredients into the wet ingredients until the cookie dough is just combined, and the chocolate chips are evenly distributed throughout the dough.

Using a spring-loaded ice cream scoop or two small spoons, scoop the dough by the tablespoonful. Drop the mounds of dough on the prepared baking sheets about 2 inches from one another.

Using moistened fingers, flatten each piece of cookie dough into a disk about 1/2-inch tall. Do not chill the dough.

Place the first baking sheet in the center of the preheated oven and bake for about 10 minutes, or until very lightly golden brown all over. Do not overbake.

Remove the baking sheet from the oven and allow the cookies to cool until firm, about 10 minutes, before transferring to a wire rack to cool completely. Repeat with the remaining cookie dough.