Mash the banana and toss it together with the raisins, the oats and the cinnamon in a bowl. Meanwhile preheat the oven onto 250 degrees.
Form the dough with a tablespoon into little balls and place them on some baking paper on a baking sheet. Put them into the oven and bake it at 180 degrees for 12-15 minutes. They may be a bit soft when you take them out, but of course already resistent. Eat them directly or let them cook down.