Place butter in a small sauce pan over medium heat. Stir constantly. Butter will melt, then bubble and then foam. Once it is foaming watch carefully to not let it burn! Once it smells nutty (mine smelled like caramel corn) remove from heat and pour into a different bowl to stop it from cooking. Let cool for 5-10 minutes.

Combine flour, baking soda and salt in a bowl. Set aside.

When the butter is cool enough to touch with your finger, beat butter and sugars (brown and granulated) in a stand mixer. Add egg and egg yolk one at a time. Scrape down the sides of the bowl as needed. Add vanilla extract and milk. 

Slowly add in dry ingredients and then chocolate chips. Let dough chill in the fridge for 2-3 hours. Don't skip this step! 

Preheat oven to 350 degrees and line cookie sheets with parchment paper.  Make dough balls a little larger than a golf ball, place on cookie sheet and sprinkle with coarse salt.  Bake for 10-12 minutes (or less depending on how soft and gooey you like them).