- Heat the oven to 190°c/fan 170°c.
- Put the haddock in a pan and cover with milk. Bring to a boil then turn off the heat, cover and leave for 10 minutes until just cooked. Lift the fish onto a plate and flake, reserving the milk.
- Cut the potatoes into 1 cm thick slices.
- Melt the butter in a pan, add the flour and cook for a minute or so. Gradually add the milk, let it thicken but be careful to not let it get too thick. Add the potatoes and cook very gently for 3 minutes.
- Add almost all the cheese to the pan and stir. Fold in the fish and parsley and put the mixture into a buttered baking dish.
- Top the remaining cheese and bake for 30-35 minutes until golden and bubbling. Serve with a green salad on the side.