Preheat oven to 180 degrees Celcius (160 degrees fanforced). Line a baking dish with baking paper.
Add cashews to a food processor and process until they become a fine crumb. (Process the oats at this step if you are after a smooth bar, otherwise leave them to the end).
Add bananas, beans, sugar, syrup and vanilla to the processor. Process until smooth.
Add the oats and process until just combined.
Pour the mix into the prepared baking dish and smooth the surface. You want the bar to be quite thin for it to cook though.
Cook for approximately 30 minutes until lightly browned on top.
Remove the cooked bars from the dish and allow to cool. Cut into bars or squares.
Store the muesli bars in a sealed container in the fridge. These bars can be frozen.