Kalua would be great I think. My daughter and I were trying to decide what would be good. Next time we might buy one of those mini bottles.
I was thinking dark rum but I am not sure. Even brandy?
It still needs the coffee.

I love tiramisu too... the real cake one. Layer upon layer of deliciousness.

When I was a child a relative used to make something called chocolate sherry cream. It was very similar but just used sponge cake rather than the sponge biscuits. Sherry was a big thing back then I recall. Not sure why.
The chocolate part was more of a mousse.

The desert above would be better with a mousse but it is more difficult than the chocolate custard and at least I know the custard has cooked eggs in it rather than uncooked ones.

p.s. could use mascarpone instead of the whipped cream.