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

In a large mixing bowl, mash the bananas until smooth.

Stir in the peanut butter and vanilla extract until well combined.

Add the rolled oats, protein powder, and cinnamon, mixing until a thick dough forms.

Fold in the dark chocolate chips.

Scoop 12 equal-sized portions of dough onto the prepared baking sheet.

Flatten each scoop slightly with the back of a spoon to form a cookie shape.

Bake for 12 to 15 minutes or until the edges are firm and lightly golden.

Remove from oven and allow to cool on the baking sheet for 5 minutes before transferring to a wire rack.