Preheat oven to 375°F.
Melt butter in an 8-inch skillet (see notes below if you don’t have an 8-inch and have to use a 10-inch!) over medium heat. Stir the butter gently for 5 to 7 minutes or until the butter is golden-brown. If you start to see little bits turn black, remove from heat immediately, we don’t want it to burn!
Remove skillet from heat and stir in the brown and white sugar until completely combined. Throw the whole skillet in the refrigerator for 5 minutes if you have room, or just let it cool down at room temperature for 10 to 15 minutes, or until the butter mixture is only slightly warm to the touch. If you don’t let it cool enough, your egg yolks will turn into gross little scrambled eggs and your chocolate chips will melt. It will be sad. Be patient! You can leave it in the fridge for as long as you want, exact timing is not important as long as the mixture is cool.
Stir in the egg yolk and vanilla extract until totally combined.
Pour the flour, baking powder, and salt into a big pile on top of the butter mixture. Use a fork to mix the dry ingredients together so that the baking powder gets evenly distributed, then incorporate the dry ingredients into the butter mixture.
Stir in the oats and chocolate chips, then pat down the dough.
Bake for 12 to 15 minutes. 12 for a ooey gooey cookie, 15 for a firmer cooker. In the video we cooked ours for closer to 15 (by accident!).
Enjoy IMMEDIATELY!