Mash the bananas with a fork or blend them in a small blender.
Add the other ingredients and combine until you get a malleable dough (you might need to add more oats). Let the mixture rest until the oven warms up.
Turn the oven temperature to 180°C and line a baking tray with parchment paper.
Make 8 medium or 10 small equal sized balls from the mixture and flatten these slightly between your palms.
Put the cookies on the prepared baking tray, then bake in the preheated oven for about 10-15 minutes until golden brown.
Cool the cookies on wire rack then transfer them to a jar or cake tin.