Add flour to a cup, then stir in sugar, cocoa, oil and water
Mix all together until you get a smooth texture. You'll need to end up with a soft, creamy mixture so if you're not totally happy with your result, add a few more drops of water.
Place into the microwave on highest setting, for 1 min 40 seconds. You may need to experiment a little with that as microwaves have different settings.
Dust icing sugar
Add a scoop of ice cream (optional; but again, why wouldn't you?) and serve immediately.