Preheat the oven to 350 degrees F.
Grease a 9×9” square baking pan and set aside.
In the bowl of a standing mixer, cream together butter, light brown sugar and granulated sugar until well combined.
Add egg and vanilla to the butter/sugar mixture and beat until combined. Set aside
In a small bowl, whisk together flour, baking soda, baking powder, and salt.
Add the dry ingredients to the wet and beat until all the ingredients are thoroughly combined.
Add 1 cup of semi sweet chocolate chips and mix until evenly distributed.
Press the cookie dough into the bottom of the prepared baking pan.
Top with remaining chocolate chips and press in slightly.
Bake for 18-25 minutes, or until the edges are set, and the top is just barely browned.
Place baking pan on a wire cooling rack and let the bars cool in the pan for at least 30 minutes (preferably longer, they hold up better as they cool).
Cut into 12 or 16 squares depending on the size you prefer and serve.