In a baking dish combine oats, brown sugar and cinnamon.
In a microwave proof jug combine peanut butter, banana & vanilla extract. Microwave for up to 1 minute to slightly melt the peanut butter. This will make it easier to stir through the oats.
Pour the peanut butter mixture over the dry ingredients and stir thoroughly until the oats are fully coated. Bake at 150 degrees C for 40 minutes, stirring every 10-15 minutes. Leave to cool for 5 minutes before stirring through chocolate chips.
Allow to cool completely before storing in an airtight container.