Preheat an oven to 175°C and line a baking tray with parchment paper.
Into a mixing bowl add the banana and peanut butter. Crush the banana until smooth and the two ingredients are completely combined.
Then pour in the rye flour, oats, and ground cinnamon, fold together to mix well.
If the peanut butter dough becomes too dry, then add extra peanut butter until the consistency is firm and workable.
Transfer the dough to a work surface and roll until 0.5cm thick using a rolling pin.
Cut the dog treats with a cookie cutter or roll using your hands to form traditional cookies.
Place the peanut butter dog treats onto the lined baking tray and bake for 15 minutes.
Once the treats are golden brown remove them from the oven and allow them to cool completely.
Store in an airtight container for up to 1 week at room temperature or 2 weeks in the refrigerator.