Begin by preheating your oven to 350°F (175°C).
In a large bowl, mash the bananas until they’re smooth.
Stir in the vanilla extract and your choice of sweetener, be it honey or maple syrup.
Add the rolled oats, mixing them in thoroughly.
Now, it’s protein time! Gently fold in the whey protein powder.
Add the walnuts, cinnamon, and a pinch of salt to the mixture. Give it a good stir until everything’s combined.
Line an 8×8 inch (20×20 cm) baking dish with parchment paper.
Transfer the mixture into the dish, spreading it out evenly.
Bake for 15-18 minutes, or until the edges turn a golden brown.
Once done, let it cool for about 10 minutes before cutting into 8 equal pieces.