Put the potatoes into boiling salted water and bring back to the boil for 2 minutes.Carefully add the eggs to the pan and cook for a further 8 minutes, or until hard-boiled, by which time the potatoes should also be cooked.
At the same time, steam the spinach in a colander above the pan. This will only take a minute. When the spinach is done, remove from the colander and gently squeeze out any excess moisture.
Drain the potatoes in the colander. Remove the eggs, cool under cold water, then peel and quarter them. Place to one side.
In a separate pan, slowly fry the onion and carrot in a little oil for about 5 minutes, then add the double cream and bring just to the boil.
Remove from the heat and add the cheese, lemon juice, mustard and parsley.
Slice the fish into strips then place in an earthenware dish with the spinach and eggs and mix together, pouring over the creamy vegetable sauce.
The cooked potatoes should be drained and mashed – add a bit of oil, sea salt, black pepper and a touch of nutmeg (if using). Spread on top of the fish.
Place in the oven for 25 to 30 minutes, or until the potatoes are golden.
Serve with some peas or greens, with tomato ketchup for those who need it.