Mister and Miss Red Nose Day Cake Jars

I love this super fun way of presenting cakes (used to send homebaking to armed forces, just have to be careful with food hygiene).  I made a vanilla sponge and condensed milk icing (yum and not at all nutritious).  I need about 50g worth of the butter/sugar for each jar and filled with no more than half (1/3 better) to leave room for the icing..  By the way, the jar takes ages to cool down so don't make it last thing at night.