Brown the butter. Place butter in a medium-sized skillet or saucepan over medium-low heat and cook until melted. Increase heat to medium and cook, stirring frequently as the butter sizzles and pops. Stir constantly, scraping the bottom of the pan with a spatula to prevent burning, and continue to stir until butter has browned (there will be lots of deep brown specks and the butter will have a toasty, nutty aroma). Immediately remove from heat and pour into a large heat-proof bowl. Allow to cool completely (until no longer warm to the touch) at room temperature before proceeding.

While butter cools, preheat oven to 350F (175C) and line baking sheets with parchment paper. Set aside.

Once the browned butter is no longer warm, add the sugars and stir well.

Add eggs and vanilla extract and stir well.

In a separate, medium-sized mixing bowl, whisk together flour, baking soda, baking powder and salt.

Gradually add the dry ingredients to the wet, stirring until completely combined.

Add oats and chocolate and stir until well distributed through the dough.

Scoop dough by 2 Tablespoon-sized scoops (43g) and drop onto prepared baking sheet (for more uniform, round cookies, roll between your palms to make a smooth ball before placing on baking sheet). Space cookies at least 2” apart on baking sheet.

Transfer to center rack of 350F (175C) oven and bake 9-11 minutes.

While cookies are still warm, sprinkle with flaky sea salt. Allow cookies to cool 5-10 minutes on baking sheet before carefully removing to cooling rack to cool completely.