Step 1

In a stainless steel skillet (or another light-bottomed pan) over medium-high heat, melt butter, swirling the pan occasionally. The butter will begin to foam, which signals the water in the butter is boiling off. (Watch closely at this stage.) Tiny brown specks of milk solids will begin to appear at the bottom of the pan; constantly stir and scrape these off using a spatula so they don't stick.

Step 2

As soon as the butter turns chestnut brown and smells nutty, remove the pan from the heat. Pour the browned butter into a heat-safe bowl.

Step 3

To the hot browned butter, add the brown sugar, stirring to combine. Set aside to cool for 15-20 minutes.

Step 4

To a medium bowl, add the flour, baking soda, salt, and baking powder. Whisk to combine.

Step 5

Once the butter mixture has cooled, add eggs and vanilla. Whisk to combine.

Step 6

Using a rubber spatula, gradually mix in the flour mixture.

Step 7

Fold in the chopped chocolate.

Step 8

Using a 3-tablespoon scoop, drop balls of dough onto a baking sheet lined with parchment paper. Cover the dough balls and transfer to the refrigerator to chill for 24 hours.

Step 9

Remove the chilled cookie dough from the refrigerator. Let it rest at room temperature for 30 minutes before baking the cookies.

Step 10

When ready, preheat oven to 350°F. Line baking sheets with parchment paper.

Step 11

Place the dough balls onto lined baking sheets, leaving about an inch between each cookie. Bake for 12-14 minutes or until golden brown. (I prefer these slightly underdone, so I will start checking at 10 minutes.)

Step 12

Remove from oven. Sprinkle flaky sea salt on the tops of the warm cookies.

Step 13

Let the cookies cool on the baking sheets for 5 minutes before transferring them to a wire rack to cool completely.