Combine all the ingredients in a food processor and process till the dough has the soft texture of your earlobe. (Adjust the amount of whole wheat flour as needed depending on the size of the banana.)
Roll out the dough to fit on your baking tray to a thickness of about 1 mm. Using a pizza cutter, or a similar utensil, cut them into desired shapes.
Poke holes into the dough with a fork. Bake in a preheated oven at 180℃ for about 20 minutes. Allow them to cool on the baking tray.