Preheat the oven to 350℉. Line 3 large baking sheets with parchment paper.

In a large bowl, beat together the butter, brown sugar, and granulated sugar on high speed for about 30 seconds. Add the egg and vanilla extract and beat on high until fluffy.

Add the flour, baking soda, salt, and cocoa to the bowl. Beat on low speed just until all the flour is incorporated. Lastly, fold in the white and semisweet chocolate chips.

Scoop about 1 tablespoon of dough per cookie onto the prepared baking sheets, leaving about 2 inches between cookies for spreading room.

Bake the pans of cookies one at a time in the preheated oven for 8-12 minutes or until the tops no longer look wet. Let the cookies cool on the baking sheet for 5 minutes before transferring them to a wire rack to finish cooling. Enjoy!