1. Preheat oven at 180°c.
2. Peel and cut potato into chunks. Boil in water until fork tender. Drain cooked potatoes, season with salt, pepper and add butter. Mash potatoes until fine or can leave it slightly chunky. Stir in milk and adjust seasoning if necessary.
3. Put prawn shells in a pot and cover with just enough water. Bring to a boil and simmer gently for 15 minutes. Use potato masher to crush the shells to extract flavour from the prawn heads. Strain and discard the shells. Reserve prawn stock for later.
4. Cut salmon, white fish into chunks and de-vein prawns. Place seafood in a baking dish and season with salt, black pepper and lemon zest. Mix well and set aside in the fridge.
5. To make the sauce, make the roux (thickening agent) first by melting butter in a pot and add in flour. On medium low heat, use a wooden spoon to stir the flour around to make sure it doesn’t turn brown colour.
6. Cook for about 3 – 4 minutes until there is a slight nutty smell. The flour should look slightly frothy.
7. Add in half of the milk and whisk to combine. The roux will turn into a big gloop. Add in the rest of the milk and prawn stock. Whisk on medium heat until there are no lumps. Season with salt, pepper and a drizzle of lemon juice. The consistency should be like melted ice cream.
The consistency should be slightly thick, smooth and lump free
8. Time to assemble. Pour white sauce all over the seafood and gently stir it around to make sure every surface it coated with white sauce.
9. Next, use a fork and spoon to spread mash potato on top.
10. Sprinkle grated cheese all over mashed potatoes.
11. Bake in the oven for 30 – 35 minutes, or until the cheese is dark golden brown. Let fish pie rest for 10 minutes before serving.
Beautiful cheese crust
Serve with greens and a lemon wedge