Place salmon fillets on a baking paper-lined oven tray. Cook in preheated 200C oven (180C fan-forced) for 15 minutes or salmon flakes easily when tested with a fork. Remove flake salmon with a fork.
Heat oil in a large saucepan and add the flour, stirring over a medium heat for 1 minute. Slowly add the milk, stirring to break up any lumps, bring to the boil, reduce heat to low and simmer for 2 minutes, stirring occasionally. Remove from heat.
Stir in nutmeg, parsley, salmon and peas. Season with pepper. Pour into a 6-cup capacity ovenproof dish. Set aside.
To prepare mashed potato, cook potatoes in large saucepan of boiling water for 15 minutes or until tender. Drain, return to pan. Add milk and mash until smooth and creamy. Season with pepper.
Spoon potato over salmon mixture, spread evenly and sprinkle with cheese. Place dish on an oven tray. Bake in preheated 200C oven (180C fan-forced) for 30 minutes or until pie is heated through and topping is golden. Serve with salad leaves.

Image credit: Joe Filshie Photography