Step 1

Preheat the oven to 200C/400F (fan).

Step 2

Place the potatoes into a pan and cover with cold water. Bring to the boil and then simmer for 15 minutes.

Step 3

Drain the potatoes and then mash with a potato masher or ricer. Stir in half of the butter, the cream and a pinch of salt and pepper. Put to one side.

Step 4

Place the milk in a large saucepan with the salmon fillets and the cod/haddock. Bring to the boil and simmer for 2-3 minutes (if you're using raw prawns, add them in for the last minute of cooking). By this time your fish should be cooked and starting to flake apart.

Step 5

Place the flaked fish and prawns (add the cold, cooked prawns at this point if using) in a large baking dish, remove and discard the skin if the fish wasn't skinless.

Step 6

Pour the cooking liquid into a jug and keep to one side

Step 7

Melt the remaining butter in the milk pan, then stir in the flour. Heat through on a medium heat whilst mixing with a wooden spoon for a minute.

Step 8

Slowly add in the reserved milk that you cooked the fish in whilst stirring with a balloon whisk (don't whisk it hard though, or you'll end up with a frothy sauce). The sauce will begin to thicken after a few minutes.

Step 9

Turn off the heat and stir through half the cheese and a pinch of black pepper.

Step 10

Pour the reserved milk back into the milk pan and heat until barely simmering - don't let it boil. A bit at a time, stir through the cornflour/water mixture using a balloon whisk. Keep adding the cornflour mix until the milk thickens. Turn off the heat and stir through half the cheese and a pinch of black pepper.

Step 11

Now it's time to assemble fish pie. Pour the sauce over the fish/prawn mixture.

Step 12

Spoon the mashed potato over the top and then use a fork to spread it out and give it a lined pattern (this gives the mash more surface area to crisp up).

Step 13

Sprinkle over the remaining cheese and place in the oven for 15-20 minutes until the cheese is melted and golden.

Step 14

Top with chopped chives and serve with peas, and sweetcorn.