In a light colored saucepan and over medium heat, add unsalted butter. Swirl the pan and keep the butter moving around constantly. Once completely melted, the butter will foam and sizzle and gradually start to brown and deepen in color. You'll notice a nutty aroma and tiny brown specks at the bottom of the pan. The whole process should take about 8 minutes. Be careful not to burn it.

Immediately transfer to a glass bowl and allow to cool.

Place a rack in the center of your oven and preheat it to 350ºF (176ºC).

Prepare an 8x8 inch square pan by buttering and lining with parchment paper, leaving an overhang for easy removal.

Combine brown butter, brown sugar, white sugar and vanilla. You can use a stand mixer, hand-held mixer or whisk by hand.

Add egg and yolk and mix until well combined. About 1 minute on medium.

Sift in flour, baking powder and salt and mix until until there are few flour streaks left. Do not overmix here.

Add chocolate chips and chopped pecans and mix just until combined.

Transfer to your prepared pan and bake for 20 to 24 minutes. It's ready when the edges are golden brown and the center has puffed up slightly. Do not overbake. It will continue to cook as it cools.

Allow to cool completely in the pan before cutting. You can slice into 9 or 16 equal pieces. Enjoy!