Well it's more of a cake in a mug, but for alliteration purposes we'll call it a muffin.
My friend sent me this recipe when I was in first year and I recently found myself with an egg to spare so it was muffin in a mug time all over again.
Here's the deets:
4 tablespoons of self raising flour
4 tablespoons of sugar
2 tablespoons of cocoa powder
3 tablespoons of milk
3 tablespoons of vegetable oil
Mix the flour, sugar and cocoa powder in a mug.
Add the egg and mix well.
Add the milk and oil and until creamy with no lumpy bits.
Microwave for 3 minutes.
It's pretty cool to watch the cake rise up in the mug!
When the time is up get a knife and stab it through the middle of the muffin. If it comes out clean it's done, if not whack it in the microwave for a bit longer.
I recommend eating it straight away while it's still warm. Perfect for if it's been snowing.
Which it has.
It can be a little bit dry so making up some hot chocolate sauce would be awesome, but I didn't think of that until I'd almost finished eating it.
(Recipe originally from wikiHow)