Pour the melted butter into the bowl of an electric stand mixer fitted with the whisk attachment and sprinkle in both white and brown sugars. Whisk on medium-low for 2-3 minutes before adding the egg, egg yolk, and vanilla extract. Switch to the paddle attachment.
In a separate bowl, whisk together the flour, baking soda, and salt. Slowly pour the dry ingredients into the bowl of the stand mixer in three stages, pausing in between until fully incorporated before adding more.
Use a rubber spatula to manually fold in the chocolate chips and dark chocolate morsels. Cover the batter bowl with cling film and chill in the refrigerator for at least thirty minutes up to overnight.
Preheat the oven to 350℉. Using either a tablespoon or cookie scoop, portion out the dough weighing 60 grams each. Line them on a prepared baking sheet, leaving 2 inches in between.
Bake for 10-12 minutes (depending on your oven). If desired, sprinkle fresh salt overtop for garnish and texture. Allow the cookies cool on the tray for 5 minutes before transferring on a wire rack to finish cooling completely.
