Preheat oven to 350 and line a cookie sheet with parchment paper.
In a small bowl add your butter , vanilla extract and sugars. Mix with a spoon or use a mixter until the mixture is fluffy.
Slowly add in the egg, flour, and cocoa powder. Using your cookie scoop, add scoops to parchment paper lined cookies sheet. Making sure there's space between each cookie when you scoop them onto the cookie sheet.
(optional) Add a marshmallow to the top of the cookie scoop on the parchment paper. This is optional.
Cook for 9-11 minutes and cool on a wire rack. Enjoy!