- 500g/1lb 2oz floury potatoes, such as King Edward or Maris Piper, peeled and cut into chunks
- 450ml/15fl oz milk
- 100g/3½oz butter, plus extra for the topping
- salt and freshly ground black pepper
- 300g/10oz raw prawns, shells on
- 400g/14oz fresh haddock fillets
- 200g/7oz un-dyed smoked haddock fillets
- 4 black peppercorns, lightly crushed
- 1 bay leaf
- several springs flat-leaf parsley
- 4tbsp plain flour
- squeeze of lemon juice
- 2tbsp double cream
- 4tbsp chopped flat-leaf parsley
- pinch of cayenne pepper
- Boil the potatoes in a large saucepan of cold salted water for 10-15 minutes, until tender, then drain well. Mash until smooth then beat in 150ml/5fl oz milk and 60g/2oz butter. Season to taste with salt and pepper, then set aside.
- Meanwhile, remove the heads and shells from the prawns, and reserve the shells. Devein the prawns and set aside.
- Put the fish in a frying pan with the remaining milk and bring to a gentle simmer for 10 minutes, or until the fish flakes easily. Use a slotted spoon to remove the fish from the pan and set aside. Add the prawn shells, peppercorns, bay leaf and parsley sprigs to the milk and simmer over a very low heat for 10 minutes.
- Meanwhile, preheat the oven to 220°C/425°F/Gas 7. Melt the remaining butter in a saucepan over medium heat. Sprinkle in the flour and cook for 1 minute. Remove from the heat. Strain the milk and gradually stir into the butter mixture. Return to the heat and simmer until the sauce thickens. Stir in the lemon juice and cream, and season to taste. Stir in the chopped parsley, cayenne and prawns, and flake in the fish.
- Spoon the fish mixture into the pie dish, top with the mashed potatoes and dot with a little extra butter. Place the dish on a baking tray and bake for 20-25 minutes, until the topping is golden and the filling is hot when you test the centre with a knife. Remove the pie from the oven and serve immediately.