These rich, nutty cookies deliver a deeper flavor than your classic chocolate chip cookie. They're crispy on the edges and perfectly chewy in the center.
Cut the butter into pieces and place in a light-colored saucepan over medium heat. Stir occasionally as it melts and foams. Continue cooking for 3 to 5 minutes until the butter turns amber and smells nutty with golden-brown bits on the bottom. Pour the brown butter into a large heatproof bowl and let it cool for 15 minutes.
Add the dark brown sugar and granulated sugar to the cooled brown butter. Whisk vigorously for about 1 minute until smooth and slightly thickened.
Add the eggs one at a time, whisking well after each addition. Stir in the vanilla extract until combined.
In a separate bowl, whisk together the flour, baking soda, and fine sea salt. Add the dry ingredients to the wet mixture and stir with a spatula until just combined with no flour streaks remaining. Fold in the chocolate chips.
Cover the dough tightly with plastic wrap and refrigerate for at least 1 hour or up to 48 hours. The longer it chills, the deeper the flavor.
Preheat your oven to 375°F (190°C) and line baking sheets with parchment paper. Scoop the dough into generous balls, about 3 tablespoons each, and place them 3 inches apart on the prepared sheets.
Bake for 10 to 12 minutes until the edges are set and golden but the centers still look slightly underdone. Immediately sprinkle flaky sea salt on top of each cookie.
Let the cookies cool on the baking sheet for 10 minutes before transferring to a wire rack. The centers will set as they cool.