Add your butter and sugar to a bowl, and beat together!
Add the egg, flour, cocoa powder and vanilla and beat again.
Add in the chocolate chips and mix in, and split evenly between two microwave safe mugs/ramekins!
Microwave for 70-100 seconds, and keep an eye on it!
Serve with extra chocolate, ice cream or anything!
Notes
I use two ramekins for these - which are a decent size but it makes the cookie look 'full'. You can use any mug that is microwave safe but the cookie doesn't really rise so beware of that!
You can take out the cocoa powder and use 90g of plain flour!
Best eaten warm and fresh.
The cookie make look raw a bit on top, but its always more cooked inside so make sure to check!