Preheat the oven to 350°F (175°C). Line a 9×13 inch baking pan with parchment paper, leaving an overhang on the sides for easy removal.
In a large mixing bowl, whisk together the melted butter, light brown sugar, and granulated sugar until smooth and combined.
Add the eggs one at a time, beating well after each addition. Stir in the vanilla extract.
In a separate bowl, whisk together the gluten free all-purpose flour, baking soda, and salt.
Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Do not overmix.
Fold in the semi-sweet chocolate chips evenly throughout the batter.
Spread the batter evenly into the prepared baking pan, smoothing the top with a spatula.
Bake for 22 to 25 minutes, or until the edges are golden brown and a toothpick inserted in the center comes out with a few moist crumbs.
Remove from the oven and allow the bar cookies to cool completely in the pan on a wire rack.
Once cooled, use the parchment paper overhang to lift the bars out of the pan. Cut into 16 squares and serve.