This one is definitely a keeper!
The carmel sauce that goes on top hardens a bit too fast, but I don't know what to do to fix it.
Mom enjoys putting a slice in the microwave, heating it for a few seconds, and puts a scoop of vanilla ice cream on top.
I think using a Jonathan or Granny Smith apple would taste good. They would stay firm longer, and you would get more of an apple taste, instead of mush. I was a little skeptical of putting the apples in it with the peels on, but it tasted ok. If you use a firmer apple, I would try peeling the apples first.
I would also suggest something to keep the top of the cake (bottom when flipped onto a plate) more moist.
I don't really have too many suggestions for this recipe, but I recommend trying it for yourself and posting any ideas.