Preheat your oven to 350°F (175°C). Line a baking sheet with parchment paper to ensure your cookies don’t stick.
In a large mixing bowl, combine the melted butter, granulated sugar, and dark brown sugar. Use a whisk or electric mixer to cream them together until the mixture is light and fluffy, about 2-3 minutes.
Next, add the large egg and pure vanilla extract to the sugar mixture. Beat until fully incorporated and smooth.
In a separate bowl, whisk together the gluten-free flour, corn starch, baking soda, and coarse kosher salt. This ensures that the leavening agents and salt are evenly distributed throughout the flour.
Gradually add the dry mixture to the wet ingredients. Stir until just combined; be careful not to overmix. Gently fold in the milk chocolate chips until evenly distributed.
Using a cookie scoop, drop rounded tablespoons of dough onto the prepared baking sheet, leaving some space between each cookie. Bake in the preheated oven for 10-12 minutes, or until the edges are lightly golden but the centers remain soft.
Remove the cookies from the oven and let them cool on the baking sheet for about 5 minutes before transferring them to a wire rack to cool completely.
