To prepare the haddock
1 Chop the haddock fillets into large chunks. Put the double cream into a saucepan with the fish, bring to the boil, cover and simmer for a couple of minutes, then remove the haddock and transfer to a plate to cool.
To make the Mornay sauce
2 In a medium-sized saucepan, melt the butter and add the flour. Whisk over a low heat for 2-3 minutes until there are no lumps. In a separate pan bring the milk to the boil with a little grated nutmeg and pour it over the cooked roux. Bring the mixture to the boil and cook for 10 minutes, stirring gently. Season, pass through a sieve and stir in the grated cheese.
Assembling the dish
3 Pre-heat the oven to 180C/Gas Mark 4. Take the four small potatoes in their skins and cut into a small dice. You will need four small ovenproof dishes. Place some haddock in each dish and cover with Mornay sauce. Crack an egg on top in the centre of each dish, sprinkle the diced potato on top and season with salt and pepper.
4 Put the dishes in a baking tin, pour in boiling water to come halfway up the sides of the dishes and bake for 8-10 minutes. The egg yolks should still be soft.
5 Serve straight from the oven. Place the piping hot dishes on a plate. To finish, sprinkle with chopped dill and cracked black pepper.