Preheat the oven to 350°F (175°C).

In a mixing bowl, combine the rolled oats and whole wheat flour.

In another bowl, mix the mashed banana, egg, and peanut butter until well combined.

Gradually add the wet mixture to the dry ingredients, stirring until a dough forms.

Roll out the dough on a floured surface to about 1/4 inch thick.

Use a cookie cutter to cut out shapes and place them on a baking sheet lined with parchment paper.

Bake for 20-25 minutes or until golden brown.

Allow to cool completely before serving to your dog.