01 - Prepare a campfire or preheat an outdoor grill to medium heat.
02 - Slice each banana lengthwise, making a deep cut to create a pocket but not severing it completely.
03 - Gently open the slit in each banana and generously fill with chocolate chips, marshmallows, and chopped nuts if using.
04 - Top each stuffed banana with 1 teaspoon of unsalted butter and sprinkle with 1 tablespoon of graham cracker crumbs, if desired.
05 - Carefully wrap each filled banana tightly in a piece of heavy-duty aluminum foil, ensuring a secure packet.
06 - Place the foil packets directly onto the hot grill grates or campfire coals. Cook for 8 to 10 minutes, turning them once, until the chocolate and marshmallows are fully melted and the bananas are tender.
07 - Using tongs, carefully remove the foil packs from the heat. Open with caution as the contents will be extremely hot, and serve immediately.