Place the butter in a heavy saucepan. Cook it over medium heat, stirring occasionally. It will bubble, then foam up and turn light brown. Watch it closely, it can burn quickly after it foams. When it's golden brown, pour it into a metal or glass bowl and let it cool for at least 10 minutes.

Preheat oven to 350°. Spray a 9x13" baking dish with non stick cooking spray; set aside.

In a large mixing bowl, whisk together the cooled brown butter, brown sugar, eggs, and vanilla extract.

Stir in the dry ingredients, then about a cup of the chocolate chips.

Press dough into the prepared pan, then sprinkle the remaining chocolate chips over the top of the dough.

Bake at 350 degrees for 27-30 minutes, or until edges are golden brown and middle is set.