Add the porridge oats, semi-skimmed milk, water, and cocoa powder to a saucepan.

Cut one of the satsumas in half and squeeze the juice into the saucepan.

Place the saucepan over low heat and cook for 4-5 minutes, stirring continuously until the oats are soft and the ingredients are well combined.

Add a drop of sugar free sweetener if desired to adjust the taste according to your preference.

Pour the porridge into a bowl, top with a square of dark chocolate, and garnish with the segments from the second satsuma.