Mix the oat flakes with the chia seeds and milk in a bowl.
Mash a relatively ripe banana with a fork and stir into the mixture.
Cover the bowl and put in the fridge for several hours or overnight - during this time the seeds form a pudding like gel.
In the morning, cut some fruit (e.g. nectarines, apples, pears etc.) into pieces and stir into the pudding. Sweeten with honey, agave syrup or maple syrup if necessary.