Preheat oven to 300 degrees. Grease a baking sheet or line with parchment paper/silpat.
Combine banana, egg, applesauce and peanut butter in a medium bowl and mash together.
Add flour and oats and stir to combine.
Flour a clean surface and roll dough out with a rolling pin, adding as much flour as you need to keep it from sticking (I had to use a generous amount).
Use a cut out of any shape (I used the top to a jar of jam for small discs) and lay each piece on the baking sheet.
Brush with egg whites if using and bake for 25-30 minutes.