It was simple and not very time-consuming to make. You could make the shortbread a day ahead, I suppose. The caramel layer will only take 10 minutes. That needs to be cool before you put on the chocolate layer, so I suppose you could go off and do something else for an hour or two.
Use Ghiradelli chips for the chocolate. You can just melt them in a bowl in the microwave. That layer also needs to cool so the chocolate hardens, before you can serve it.

I'm going to make some now! :-)