This breakfast is a hug in a bowl :)
Put the porridge oats and the grated apple in a saucepan, and pour over the milk and add the cinnamon if using. Gently bring to the boil and then reduce the heat to a simmer and cook for 6-7 minutes, stirring from time to time and watching carefully that it doesn’t stick to the bottom of the pan.
Once the porridge is cooked, stir in the chopped walnuts and transfer to a warmed bowl and serve straight away