Set the oven to 200C/180C fan/gas mark 6.

Place the fish pie mix in a baking tray then add half the milk, a few cubes of butter and the bay leaf. Place the tray in the oven for 15-20 minutes. Pour off and reserve the liquid, remove any skin from the fish and flake the flesh. Leave the oven on at the same temperature.

Make the sauce by melting the remaining butter in a large saucepan over a low to medium heat then stirring in the flour. Gradually add the liquid from step 2, stirring well after each addition. Once all the liquid is added, pour in the remaining milk, season well and simmer for 3-4 minutes.

Add the fish to the sauce together with the eggs, parsley and capers. Check the seasoning and adjust as necessary, then add the lemon juice. Pour the mixture into a large buttered baking dish.

For the topping, mash the potatoes by hand, finishing them with a hand blender for maximum smoothness, adding the milk and butter in the process. Season well and add the nutmeg.

Spread the potatoes evenly over the fish mixture and top with the grated cheese.

Bake the fish pie on a high shelf in the oven for 30-35 minutes until heated through and golden brown on top.

Serve on warmed plates.