100ml White wine
500g mussels
250g cod, or haddock
175g un-dyed smoked cod, or haddock
150ml Milk
50ml double cream
1 onion, finely sliced
1 fresh bay leaf
30g plain flour
30g Butter
1 tbsp Parsley, chopped
salt and fresh ground black pepper
100g large peeled Prawns
For the potato topping
500g Potatoes, (Maris Piper or King Edwards), peeled and diced
30g Butter
pinch Nutmeg
50g Parmesan cheese, (or substitute Gruyere or mature cheddar cheese)
Preheat the oven to 200C/gas 6. Lightly butter a medium sized gratin dish.
Pour the wine into a large saucepan and add the mussels. Cook over a high heat for 2-3 minutes or until the shells have opened. Remove from the heat and leave until cool enough to handle. Remove the mussels from the shells, discarding any shells but reserving the cooking liquor.
Put the fish into a large pan and pour over the milk and cream. Add the onion and bay leaf and bring to a gentle boil. Simmer for 5-6 minutes or until the fish is cooked through. Remove from the fish from the pan and reserve the cooking liquid. Melt the butter in a saucepan. Stir in the flour and cook for 2-3 minutes.
Slowly add the reserved milk and cream from the fish and the reserved liquor from the mussels, stirring continuously. Season to taste and add the chopped parsley.
Scatter the fish, mussels and prawns in the base of the gratin dish. Pour over the sauce.
Meanwhile, cook the potatoes in a large pan of salted water for about 15-20 minutes, or until tender. Drain.
Mash the potatoes and season with salt, freshly ground black pepper and nutmeg. Spoon the mashed potatoes over the fish in an even layer. Sprinkle over the cheese.
Bake for 20-30 minutes, until piping hot and golden brown. Serve immediately.