Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.

In a mixing bowl, mash the ripe banana using a fork or potato masher until smooth.

Add the natural peanut butter and egg to the mashed banana, mixing until well combined.

Gradually incorporate the whole wheat flour and rolled oats into the mixture, stirring until a dough forms.

If the dough is too dry, add water one tablespoon at a time until it reaches the desired consistency.

For a chewy texture, roll the dough to about 1/4 inch thickness; for crunchier cookies, roll it thinner.

Use cookie cutters to cut out shapes or simply slice the dough into squares.

Place the cut cookies onto the prepared baking sheet, leaving a little space between each one.

Bake in the preheated oven for 20–25 minutes, or until golden and firm.

Allow the cookies to cool on a wire rack before serving them to your dog.