Bring the water and milk to a boil in a milk pot. Then stir in the oat flakes and simmer for about 5 minutes over a medium heat, stirring occasionally.
Meanwhile, cut the bananas into slices or pieces.
The porridge is ready when the liquid has been completely absorbed by the oat flakes and the mixture turns into a nice, creamy paste. Remove from heat, pour into a bowl and mix with bananas and maple syrup.