A long time ago I was at a restaurant, and was served for dessert a
sort of chocolate cake/torte/pie.

This thing was unreal. It was dense like a piece of cold fudge and
had three layers, each a different color of chocolate. It was about
an inch high total.

Would anyone be able to help out with a recipe for this wonder? I'd
like to make it for Thanksgiving alongside the apple pie!

Thanks!