Put pie tin in dutch oven, resting on 3 or 4 stones or wads of aluminum foil.
Prepare cake mix according to the box and pour into pie tin.
Mash the 2 bananas and pour into pie tin.
Melt the butter and add the cinnamon, flour, and brown sugar and mix together. Sprinkle cinnamon-flour mixture on the mashed bananas.
Cover and bake for about 25 minutes.
Insert a butter knife through the center and if it comes back clean it is ready.