Preheat the oven to 180 degrees celsius.
Boil the potatoes in water for about 15 minutes until soft but not broken. Drain and mash them to a pulp.
In a pan fry the fish in a little oil – still in the skin – until lightly golden.
Drain and flake the fish and add to the potatoes.
Add the milk and spring onions to the potatoes and fish. Mix in the creme fraiche and season with salt and pepper to taste.
Put the mixture into an ovenproof dish and spread the cheese over the top.
Bake in the oven for 25 minutes.
Serving Suggestions: Top with finely chopped chives and serve with sweetcorn and peas.