In a large bowl, mash the bananas until smooth. Whisk in the almond butter, then add eggs one at a time, making sure each is thoroughly incorporated into the mixture. Stir in the cinnamon. Heat a large cast-iron (or ceramic skillet) over medium-high heat. When the skillet is hot enough that a drop of water splashed on it sizzles and bounces, add the coconut oil. Scoop 2 tablespoons of the batter per pancake onto the skillet, leaving room for them to spread. Cook 2 to 3 minutes, or until the bottom is set, before flipping. Cook on the opposite side for an additional 2 to 3 minutes. Serve topped with sliced bananas and cocoa nibs.