For the millet flake porridge with apple and banana, peel the apple, remove the core and cut into small pieces. Heat with a little water and boil for a few minutes, mash.
Peel the banana and mash it with a fork and mix it with the apple porridge. Bring the water and oat milk to a boil, add the millet flakes and let it boil down, stirring often.
When the liquid is almost gone, remove the pot from the heat and let it cool a bit, pour it into a bowl.
Add the fruit porridge and serve.