Another recipe from the same site can be found here.
I no longer had an 8" x 8" tin so bought a reduced price non stick one, not just for this but other recipes as well.
I lined it in both directions so the entire thing was lined. Once everything was in there, I pressed it down with a potato masher.
Herewith our version. As you can see, we cut them into 16 squares rather than 8 fingers. They go a little soft after a few days and are slightly sticky on the bottom but gorgeous: