Mash the bananas in a bowl until smooth with a few small lumps.
Add the oats, cinnamon, and salt. Stir until fully combined. The mixture should be thick and slightly sticky.
Fold in the chocolate chips or nuts if using.
Grease a cast iron skillet or a sheet of heavy-duty foil with coconut oil or butter.
Spoon the batter into small rounds on the skillet or foil, flattening each slightly.
Cook over medium campfire coals or a camp stove for 5-6 minutes per side, until golden brown and set.
Let the cookies cool for 2 minutes on a wire rack or plate before serving. They firm up as they cool.