In a mixing bowl, combine the melted butter, brown sugar, and granulated sugar. Whisk.
Crack in the egg and add the vanilla extract. Whisk again until fully incorporated.
Add the flour, baking soda, and salt into the wet mixture. Gently fold until a dough forms.
Fold in most of the chocolate chunks, saving a handful for topping.
Divide the dough into 10 equal portions and shape them into balls. Top with the reserved chocolate chunks. Place them on a baking sheet lined with parchment paper and refrigerate for 30 minutes.
Preheat your oven to 350°F.
Bake for 10-12 minutes, or until the edges are set but the centers look slightly underbaked.
Remove from the oven and let the cookies cool on the baking sheet for 5 minutes, then transfer to a wire rack to cool completely.