Preheat your oven to 350°F (175°C). Line your 9x13 inch baking pan with parchment paper, leaving some overhang for easy removal later.
In a large mixing bowl, whisk together the melted butter, light brown sugar, and granulated sugar until well combined. Add in the egg, egg yolk, vanilla extract, and maple syrup (if using). Mix until smooth and creamy.
In another bowl, whisk together the flour, baking soda, and salt. Gradually add the dry ingredients to the wet mixture, stirring until just combined. Be careful not to overmix!
Gently fold in the chocolate chips with a spatula, ensuring they are evenly distributed throughout the batter.
Pour the batter into your prepared baking pan, spreading it out evenly. Bake in the preheated oven for 25-30 minutes, or until the edges are golden brown and a toothpick inserted in the center comes out clean.
Once baked, remove the pan from the oven and allow it to cool on a wire rack. After about 10-15 minutes, use the parchment paper to lift the bars out of the pan and let them cool completely before slicing into squares.
