Place brown sugar, flour, cinnamon, cocoa powder, chili powder, salt and chilled butter in a bowl; mix together using a fork or a pastry fork until it resembles coarse crumbles. Or place all in a food processor and pulse a few times until it is crumbly; remove and place in a bowl.
Add in the cereal and stir until well-combined; set aside.
Add one tbsp of butter to the bottom of a baking dish or cast iron pan.
Sprinkle with the divided cinnamon and brown sugar.
Arrange the split bananas in the pan, cut to fit as needed as they might not fit whole.
Dot with the remaining divided butter.
Sprinkle with the remaining divided cinnamon and brown sugar.
Spoon the crumble over the bananas as evenly as possible; it will be clumpy.
Bake, uncovered for 15 minutes or until the bananas have reached the desired softness.
Remove from the oven, and allow to rest for 5-10 minutes, but serve while still warm.
I used my cast iron skillet which resulted in a slight blackening of the bananas. Still tasty, just discolored.