In a saucepan over medium heat, melt the butter. Continue cooking, stirring frequently, until the butter turns golden brown and gives off a nutty aroma. Remove from heat and let it cool for about 10 minutes.
Preheat your oven to 350°F (175°C). Grease a 9x13-inch baking pan or line it with parchment paper for easy removal.
In a large mixing bowl, whisk together the browned butter, dark brown sugar, and granulated sugar until well combined. Add the eggs, egg yolks, and vanilla extract, mixing until smooth.
In a separate bowl, whisk together the flour, cornstarch, baking soda, baking powder, and salt.
Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Fold in the chocolate chips and chocolate chunks.
Spread the cookie dough evenly into the prepared 9x13-inch pan. Bake for 22-25 minutes, or until the edges are golden brown and the center is just set.
Let the cookies cool in the pan for at least 20-30 minutes before slicing into bars. Enjoy warm or at room temperature!
