Preheat your oven to 175°C / 350°F.
In a bowl, mash the banana until smooth.
Add the peanut butter and protein powder, mixing until a thick dough forms.
Scoop small portions of dough onto a baking tray lined with parchment paper. Flatten slightly with a fork.
Bake for 10–12 minutes, or until the edges are lightly golden.
Allow to cool for a few minutes before enjoying.