As said, pierce surface (turn it over if top would spoil) and spoon over liberal amounts of preferred liquid. I'd use brandy, but once tried a mix of Tia Maria and brandy and it tasted good. :) Wrap in kitchen foil and leave to soak.
Thank you all, a few good ideas there to try, I do hate to waste anything, soaking some in fruit juice and putting it under custard sounds good, and I will try the apple in the tin with some of it as well as its rather a large cake. Happy new year to you all.