Chocolate Cake in a Cup

I don't remember where I got this recipe originally, (probably in an e-mail) put I sent it to my niece Dani and she made it recently. It sounds easy enough to do and I'm still thinking about making one. The picture is how hers turned out. Where's my fork?
MINUTE CHOCOLATE MUG CAKE
1 Coffee Mug
4 tablespoons flour(that's plain flour, not self-rising)
4 tablespoons sugar
2 tablespoons baking cocoa
1 egg
3 tablespoons milk
3 tablespoons oil
3 tablespoons chocolate chips (optional)
Small splash of vanilla

Add dry ingredients to mug, and mix well . Add the egg and mix thoroughly.
Pour in the milk and oil and mix well.
Add the chocolate chips (if using) and vanilla, and mix again.
Put your mug in the microwave and cook for 3 minutes at 1000 watts. The cake will rise over the top of the mug, but don't be alarmed!
Allow to cool a little, and tip out onto a plate if desired.
EAT! (this can serve 2, if you want to share!)