Put the oat flakes, milk and water together in a saucepan and bring to the boil over high heat. Always stir well so that nothing burns. Let everything swell briefly on a low heat.
Add the porridge to the banana mash, fold in and serve immediately. Sweeten with honey or sugar, if you like.
Instead of bananas, the porridge also tastes good with compote, cherries, red fruit jelly, raspberries, etc.