To brown the butter, grab a light colored pan (this helps with being able to spot when the butter is browned enough) and place it over medium heat.
Add the cubed butter to the pan and continuously stir with a wooden or rubber spoon to keep the heat moving evenly.
The butter will quickly melt and start to foam and sizzle. This is good! Keep things going for another 5-8 minutes until the butter turns a nice golden brown. Hint: Once it starts to smell nice and toasty and nutty, you are about 3 minutes away from it being done!
Immediately remove the butter from heat and place it into a heat proof container to completely cool to room temperature.
While the butter cools, pre-measure the rest of the ingredients into small bowls. Be sure to separate the egg yolk from the egg white as this recipe only uses the egg yolk!
In a medium bowl, whisk together the cooled butter, egg yolk, both sugars and vanilla.
At first the ingredients will look a little like apple sauce, but keep whisking until everything is smooth and the sugars are fully dissolved.
Add the flour, precisely measured baking soda and salt to the bowl.
Mix together with a rubber spatula until just combined.
Add the chocolate chips and work them into the dough.
Either divide the dough into two equal parts or keep it together as one giant cookie! Regardless of the number of cookies, form the dough into a ball and place onto a parchment lined baking sheet.
Then, using your palm, flatten the cookie down so it’s a bit flatter. This will help for the cookies to bake evenly.
Before putting the cookie(s) into the oven, add a few extra chocolate chips to the top of the dough.
Bake the cookies for 9-11 minutes or until the edges just begin to turn golden.
Top with a bit of sea salt as soon as they are fresh out of the oven.
Then, allow the cookies to cool for a few minutes on the warm pan before moving to a cooling rack.