Preheat the oven to 180c/350f.
Mash the bananas in an oven proof dish, then add all of the remaining ingredients, stir to combine, and gently flatten with the back of a spoon.
Bake for 25-30 minutes (it will be slightly firm to the touch, and will firm up as it cools).
Leave to cool in the dish fully then slice and serve.
Store in an airtight container in the fridge for 5 days, bench for 2 days, or freeze individual portions for 3 months.