To make the mug easier to wash up, rub the inside with a bit of butter.
Put the remaining butter in the mug with the chocolate and microwave on high* for 40 seconds.
Stir together with a fork until the chocolate and butter are melted and smooth.
Add the flour, egg, sugar and baking powder and beat until smooth again.
Microwave on high for 25 seconds then drop the Bonne Maman Strawberry Conserve onto the mixture.
Microwave on high for a further 35 seconds or until just firm on top.
Leave to cool for 1 minute then add a fresh strawberry and some icing sugar and eat straightaway.
*For an 800W microwave
Limited edition Bonne Maman Strawberry Conserve and gingham mug gift sets are available from Asda stores nationwide.