To bake over a campfire grill, use a disposable tin pan, or a reusable one you don't mind washing. Grease the bottom of the pan with butter or oil before filling it, and grease a sheet of tin foil before covering it. Check it often to make sure it is not burning.
One box of yellow cake mix, prepared according to instructions with water, oil and eggs.
One can of apple pie filling.
A quarter cup mixture of dry oatmeal, brown sugar and cinnamon.
Spread the apple pie filling in a 13x9" pan. Cover with the prepared yellow cake batter, and spread evenly. Top with the cinnamon topping. Bake according to the cake instructions, about 35 minutes. Enjoy with ice cream if at home!