Seafood

Cook potatoes in salted cold water until tender, drain, dry briefly and mash with 1 tbsp olive oil; season.
Bring milk to the boil, add the fish, remove from heat and stand 3 minutes, reserve the milk, pat the fish dry and flake into an ovenproof dish discarding skin and bones.
Heat the remaining olive oil, stir in the flour and cook briefly, gradually add reserved milk, grate in nutmeg, bubble until thick then stir in the cream.
Preheat the oven to 375°F, grate the artichokes and add them to the dish with the leek, prawns and herbs, stir lemon zest and juice into the sauce then pour the sauce over and mix gently.
Spoon the mashed potato over the fish mixture, make peaks with a fork, sprinkle over the grated Gruyère and bake until golden and bubbling.