The first thing you need to do is brown the butter. I have a great video how to do this on my instagram. Basically let your butter melt over a low flame. Once it's melted you need to pay attention and stir it constantly. The milk solids will start to toast and will give off a nutty aroma. Watch carefully and remove from heat when it is 80% done. It can burn in a second.
While your butter is cooling, lets get started. Combine both sugars in a large bowl. I use a stand up mixer, fitted with a paddle attachment.Whisk together flour, sugar, salt and baking soda together in an additional bowl and set aside.
Once butter is cooled enough, scrape all the butter and bits into bowl with sugar and start to beat. You want a light in color and fluffy consistency.Add eggs and egg yolks, one at a time, beating after each. Everything should be smooth and well incorporated.
Add the flour mix in two additions. Do not over mix. This will develop the gluten and make a tough cookie. You can finish mixing with a spatula in a folding motion.Fold in oats then chocolate chips. Make sure everything is dispersed evenly.Let chill in fridge for 20-30 minutes.Preheat oven to 375°
Portion the dough and roll into balls. I like to use a dasher/icecream scoop to get even portions. I even weigh them. 2 ounces is a great size cookie.Place about 2" apart on a parchment lined baking sheet.
Bake for 18 minutes, rotating half way through baking.Let cool on pan for 5 minutes then transfer to rack to cool completely.