Mix flour, sugar and cocoa:
Pour in milk and oil, and mix well
Put in microwave for 3 minutes on maximum power (1000watt)
Wait until it stops rising and sets in the mug
Tip contents out of mug onto saucer and enjoy!
See the original at Dizzy Dee blog
I tried it and it works a lot better in a small bowl, and with some ready made frosting, I see obesity in my near future.