Preheat oven to 180C Fan.
Using the cooking oil spray, lightly grease a small oven proof casserole dish.
Mash the bananas in a large bowl then stir in the porridge oats.
In a separate Pyrex bowl whisk together the milk, yogurt, honey, and egg.
Pour the liquid mixture into the large bowl with the banana oats mixture, add the vanilla and cinnamon and mix well together.
Spoon the mixture into the greased baking dish.
Place the baking dish into the centre of your oven and for 35 - 40 minutes until set and lightly golden brown.
Remove from oven and allow to cool a little before serving.
Serve warm in bowls as squares or broken up with a little more honey, yogurt, and some extra sliced bananas.