Preheat the oven to 350 ° F / 175 ° C.
In a medium bowl, mash the bananas with a fork until no large pieces remain.
Add the oatmeal and raisins or cranberries and mix well with a spatula.
On a cookie sheet lined with the Silicone Baking Sheet, divide the dough into 12 equal portions. Using your hands, press firmly so that the bananas act as a bond for the cookie.
Bake for 10–12 minutes, until cookies are slightly golden.