A great friend of mine had a fantastic recipe (which I can't get hold of, because it died with her, I'm afraid)
Basically, it was a standard rich fruit cake, but with a thick layer of marzipan baked into it. It had masses of pecan nuts in it too...
So, I'm guessing that a fruit cake made with almond flour, berries instead of sultanas and raisins, lots of pecans, orange peel, cherries (not sweetened), booze, a marzipan layer, and no icing...
Would be rock hard, lower carb and a mouthgasm.