Boil 1 litre of water, then reduce the heat to simmer. Add the haddock for about 10 minutes until tender.
Drain the haddock, keeping the water to use later as a stock. Flake the haddock roughly, discarding the skin and bones.
Heat the butter in a pan. Add the onion and fry until soft. Stir in the flour and cook for 1 minute.
Gradually add the stock and bring to the boil, stirring constantly. Add the potatoes and carrots and simmer for about 10 minutes until tender.
Stir in the flaked fish and cream. Season well and serve.
If you have problems chewing or swallowing, liquidise the soup in a blender or food processor (and sieve if necessary).
Then reheat it, without boiling, before serving. To make it more varied and easier to prepare, use a fish pie mix instead of the haddock.