Line a cookie sheet with parchment paper and set to the side.
In a medium bowl add the butter and melt. Add sugar, brown sugar and vanilla extract and mix until well combined. Crack the large egg in a small bowl and whisk until all combined and then measure out one tablespoon and add to the wet ingredients.
Mix the dry ingredients (flour, cocoa powder, baking soda, salt) and mix until it begins to form a dough. Add in the chocolate chips of choice and then some sprinkles if you're feeling festive. Divide the cookie dough in two and form into balls of dough. Decorate the tops of the cookies with chocolate chips.
Bake cookies for 8 to 10 minutes.
Allow the cookies to cool on the baking pan for 5 to 10 minutes before enjoying.
If there are leftovers store them in an airtight container for up to 3 days.