Preheat your oven to 350 degrees F. Line your baking sheets with parchment paper or a silicone baking mat.
In your stand mixer, cream together the butter and sugar. Add the egg and mix until combined. Add the vanilla, salt, baking soda, and cocoa powder, and mix until you have a smooth dough. Reserve approximately 2 Tablespoons of each of the white and chocolate chips for pressing into the tops of the cookies. Stir in the rest of the chips until distributed throughout.
Scoop the dough using a 1 1/2 Tablespoon cookie scoop and drop 3 inches apart on your baking sheets. Bake for approximately 10 minutes. They will lose their doughy shine on the top but will still be very soft when they are done.
Immediately after they come out of the oven, press a few of the reserved chips into the tops of the cookies.
Allow to cool on the baking sheet for several minutes to allow the cookies to firm up before moving to a cooling rack.