01 -
Heat unsalted butter over medium heat in a saucepan until melted and simmering. Continue cooking until it emits a nutty aroma and turns golden brown, about 5 minutes. Measure out 6 tablespoons of browned butter and transfer to a small bowl. Refrigerate until it reaches the consistency of softened butter.
02 -
In a medium bowl, whisk together the all-purpose flour, baking powder, baking soda, and salt until evenly combined. Set aside.
03 -
In a large mixing bowl, beat the cooled brown butter with brown sugar and granulated sugar using an electric mixer on high speed until the mixture is light and fluffy, approximately 2 to 3 minutes.
04 -
Incorporate the egg yolk and vanilla into the butter-sugar mixture. Mix on medium-high speed until the mixture becomes pale and fluffy, about 1 to 2 minutes.
05 -
Reduce mixer speed to low and gradually add the dry ingredients to the wet mixture. Mix just until combined to avoid overworking the dough.
06 -
Using a rubber spatula, gently fold in the semi-sweet chocolate chips until evenly distributed throughout the dough.
07 -
Form the dough into a large ball and gently press it down to create a disk approximately 1 1/2 inches thick.
08 -
Place the dough disk in the center of a parchment-lined baking sheet. Sprinkle with 2 tablespoons of semi-sweet chocolate chips on top. Bake in a preheated 350°F (175°C) oven for 21 to 24 minutes or until the cookie is golden brown around the edges.
09 -
Immediately after baking, sprinkle additional chocolate chips and flaky sea salt on top. Allow the cookie to cool on the baking sheet for 15 minutes before transferring to a cooling rack to cool completely or serve warm.