Add the butter to a light-bottomed medium pan and turn flame on to a medium heat. It will begin to sputter and foam.
Continue to stir the butter and keep on a medium heat, ensuring the solids do not burn at the bottom. The aromas from the browned butter should be intense with nutty and buttery notes.
Let the butter brown; keeping an eye on the butter for 3-4 minutes and turn off the heat.
Scrape the browned bits and the browned butter into a bowl and set in the fridge for approximately 1 hour.
For the Bars
Preheat the oven to 350º.
Cream the browned butter and sugars together with a hand mixer.
Add in eggs one at a time, then pour in the vanilla and whisk to combine.
To the same bowl, add in flour and baking soda and mix.
Fold in the chocolate chips and pecans.
Once the batter is formed, pour the batter into a 9x9 baking tin lined with parchment. Spread evenly so that the batter is distributed throughout the tin.
Bake in the oven for 20-22 minutes, letting cool for 15 before slicing.