You peel the bananas and put them in a bowl (you can also puree them beforehand). Then you put the oat flakes on the bananas and mix everything together (if you haven`t mashed the bananas, you just mash the whole thing with your hands), then you form small cookies with your hands.
These are then placed in the oven for about 15 minutes at 150 ° C top / bottom heat until they turn light brown. If you add cocoa powder, you should take about 1 - 2 teaspoons, but the dough will be very sticky afterwards.