1. Put the butter in a mug and melt in the microwave for 30 seconds.
2. Now add the sugar, egg and flour (in that order) to the melted butter and beat until smooth.
3. Add one spoonful of jam and then microwave for around two minutes (keep checking to make sure it doesn’t overflow and be careful as the mug will get very hot).
4. Sprinkled with a little more sugar and a dollop of jam
5. Let it cool and EAT!