In a large mixing bowl, mash the ripe bananas thoroughly using a fork until smooth.
Add the natural peanut butter, honey, and vanilla extract to the mashed bananas and mix well until fully combined.
Stir in the ground cinnamon and salt until evenly distributed.
Add the rolled oats and chopped walnuts to the wet mixture and fold gently until all ingredients are incorporated into a sticky dough.
Line a loaf pan (8×4 inches) with parchment paper or lightly grease it.
Transfer the mixture into the prepared loaf pan and press it down firmly and evenly to form a compact loaf shape.
Cover the loaf pan with plastic wrap and refrigerate for at least 2 hours to allow the mixture to firm up.
Once chilled and set, remove the banana bread from the pan using the parchment paper and slice into 8 equal pieces.
Serve chilled or at room temperature.