Step 1
Preheat oven to 200°C. Place the salmon, white fish, prawns, leek, carrot, milk and bay leaf in a large deep frying pan over medium-low heat. Bring to a simmer and cook for 2 mins or until fish is almost tender. Remove from heat. Remove bay leaf and discard. Use a slotted spoon to transfer the fish, prawns and vegetables to a heatproof bowl. Set aside to cool slightly.
Step 2
Meanwhile, strain the milk from the pan through a fine sieve into a jug. Melt the butter in a large saucepan over medium heat. Add the flour. Cook, stirring, for 2 mins or until mixture bubbles. Add the strained milk and cook, stirring constantly, for 5 mins or until sauce boils and thickens. Remove from heat. Set aside for 15 mins to cool.
Step 3
Coarsely flake the salmon and white fish. Add to the cooled sauce mixture with the remaining prawn mixture, cream, peas, chives and dill. Season. Spoon into an 8-cup (2L) baking dish. Place on a baking tray.
Step 4
Lightly brush the rim of the baking dish with a little egg. Place the whole pastry sheet over the filling to enclose, pressing around the rim of the dish to seal. Use a sharp knife to trim excess pastry. Lightly brush pastry with egg.
Step 5
Use a small sharp knife to cut 1 fish shape from the remaining pastry. Use a small round cutter to cut discs from the pastry to make scales and an eye. Arrange on the fish shape. Use the cutter to cut discs from pastry for bubbles. Arrange the fish and bubbles over the pie. Lightly brush the pastry with egg.
Step 6
Bake for 20 mins or until pastry is golden brown and puffed. Set aside for 5 mins to cool slightly before serving.