I found this on the internet. I am not a cook either but I imagine you could use the oven or the microwave just stick to allowed items. Maybe I'm wrong but I would think just apple slices with some spices maybe nutmeg, cinnamon and a little sweetner sprinkled on top would also work.
Baked Apple Dessert for the Campfire
Any of the following or all:
Core the center of the apple, trying to leave the very bottom intact. Fill the center with desired items. Double wrap in heavy duty aluminum foil. Put in hot coals for 20 minutes. Let it partially cool before unwrapping.