I've only ever tried this on a campfire but theoretically it should work the same way in an oven.

Ingredients
-banana
-peanut butter
-chocolate chips
-marshmallows
-whip cream

Instructions
-Preheat oven to 300ish
-Slit banana (still in peel) lengthwise then stuff as many things (not the whip cream but the others on the ingredient list) in as possible.
-Wrap entire thing in foil and place in oven
-Wait 5 to 10 minutes
-remove and unwrap carefully
-put whip cream on top
-enjoy instant blissful cardiac arrest