• Prepare the tin and oven
• Preheat oven to 175°C (fan‑forced ~165°C).
• Lightly grease or line a 20 × 30 cm slice tin (or similar) with baking paper.

Make oat flour

• Add the rolled oats to a blender or food processor.
• Blend until they form a coarse flour.

Mix wet ingredients

• In a large bowl, mash the bananas until smooth.
• Add almond butter and maple syrup/honey.
• Mix until well combined.
• Add dry ingredients
• Add the oat flour, ground flaxseed, cinnamon and protein powder (if using) to the bowl.
• Stir until everything is just combined.
• Gradually add ¼–½ cup milk, a little at a time, until you have a thick but spreadable batter (it should hold together but not be crumbly).
• Add chocolate chips (optional)
• Fold in the dark chocolate chips if using.
• Spread the mixture evenly into the prepared slice tin, pressing it down with a spatula so the top is fairly level.
• Bake for about 15–20 minutes, or until the edges are lightly golden and the centre is just set (you want them soft, not dry).
• Allow to cool in the tin for at least 15–20 minutes.
• Lift out using the baking paper and cut into 10–12 bars.
• Store in an airtight container in the fridge for up to 3–4 days, or freeze individually for later.