Add flour, sugar and cocoa powder together in a large mug.

In a small bowl, add milk, egg and vanilla exract. Mix well.

Add bowl to mug and stir untill smooth. Add milk for extra liquid.

Cover with cling film ensuring there are no gaps or holes.

Put in the microwave for 1min 40secs.

Take care when taking out of microwave. Run a knife around the edge of the mug and turn upside down on a plate to serve.

For added "pizazz" to impress your friends, drizzle a sauce of your choice over the cake or simply serve with double cream... mmmmmmm :-)