Bring the pint of water to the boil then simmer. Peel and chop the apples as finely as possible  and add to the water. Peel and mash the bananas and also add to the water along with the sugar.

Simmer for 15 minutes then sprinkle in the arrow root while stirring. Keep stirring while you simmer down to a thick liquid.

Once thick and lump free (if still lumpy pass though a sift) and then pour into containers.  Leave to set in the fridge for a couple of hours, then serve