Begin by browning the butter. Add the butter to a pan over medium heat. When it melts begin to stir the butter. After a couple minutes it will start to bubble -- continue stirring. After another couple minutes the butter will begin to foam up. Keep stirring and you will begin to smell a nutty aroma and see brown in the butter. Take it off the heat and pour the butter into a bowl. Transfer the butter to the freezer for 15 minutes to cool down.
Add the chilled brown butter and brown sugar to a bowl. Using a stand mixer or hand mixer, mix for 2 minutes. Add the eggs, yogurt, and vanilla. Mix until combined.
Add flour, oats, cornstarch, baking soda, and salt. Mix until flour is just combined. Add chocolate chips and pulse until they're evenly distributed.
These cookies are best if the dough chills overnight. So if you have time, cover the dough and let it chill in the fridge overnight. Take it out 15 minutes before you want to scoop the dough then proceed with the next step. IF you can't wait (which sometimes you just can't!), the dough does not have to be chilled. It can be scooped out immediately after mixing it up and baked. The cookies will still taste amazing, they just don't bake quite as well.
Preheat the oven to 350. Using a 1/4 cup cookie scoop, scoop out dough onto a greased or lined cookie sheet. Bake at 350 for 8-11 minutes, until the top of the cookies are slightly golden brown. Top with some flaky salt and let cool on the baking sheet for 5 minutes. Transfer to a cooling rack and enjoy!
