Season chicken with salt and pepper. Sear over medium heat in a large skillet and continue to cook until internal temperature has reached 165F. Set aside to cool for a few minutes before chopping into bite-sized pieces.
Preheat the oven to 450F. Cut the loaf in half lengthwise. Pick out a little of the breading in the middle to create some room for the fillings. Drizzle with olive oil and bake for 5 minutes, cut side up, to create a slight crust. Remove from oven and set aside.
Divide chicken among both pieces of crusty French bread. Drizzle with buffalo sauce and then evenly top with banana peppers, red onions, blue cheese crumbles, and shredded cheese.
Bake for 15 minutes, or until cheese has melted. Broil for 1 - 2 minutes at the end, if desired. Cool for 5 minutes before slicing. Enjoy immediately.