Fish Pie with Rosti Topping Recipe

Ingredients

• 200ml (7fl oz) whole milk
• 400ml (14fl oz) fish stock
• 125g (4½oz) butter
• 50g (2oz) plain flour
• 1tsp English mustard powder
• 150ml (¼pt) double cream
• 10g (¼oz) chives, finely chopped
• 700g (1lb 9oz) Maris Piper potatoes
• 2tsp sea salt
• 40g (1½oz) unsalted butter, melted
• 50g (2oz) mature cheddar, finely grated
• 250g (9oz) smoked haddock, skinned
• 400g (14oz) skinless salmon fillets
• 400g (14oz) skinless cod fillet

You will need:

• 1.7 litres (3 pint) dish

Method

1. Heat the oven to 200C, 180C fan, 400F, gas 6. Mix the milk and stock in a jug, set aside. Melt 50g (2oz) butter in a heavy-based saucepan then stir in the flour and mustard powder to make a smooth paste. Gradually whisk in the milk and stock mixture until you have a thick, smooth sauce. Stir in the cream and chives and season to taste, then set aside.

2. Grate the potatoes, place in a sieve, add half the salt. Squeeze out as much liquid as you can with your hands. Leave to drain for 10 minutes. Repeat the process with the remaining salt, leave for another 10 minutes and again squeeze to remove as much moisture as possible. Melt the butter in a sauté pan then fry for 1 to 2 minutes, stirring. Cool for a few minutes then mix with the cheese and pepper. Set aside.

3. Cut the fish into large chunks, and place on the base of an ovenproof dish. Pour over the sauce then top with the grated potatoes in an even layer. Place on a baking tray in the oven and cook for 40 to 45 minutes or until heated through and bubbling.