Place the eggs in a small saucepan of cold water. Bring to the boil over high heat. Reduce heat to medium and gently boil, uncovered, stirring occasionally, for 8 minutes. Drain, then cool under cold running water. Peel and quarter.

Meanwhile, to make the mash, cook the potato and celeriac in a large saucepan of boiling water for 10 minutes or until tender. Drain and use a potato masher to mash until smooth. Add the butter and sour cream and stir until well combined. Stir in the Tabasco sauce.

Preheat the oven to 220C/200C fan forced. Melt the butter in a frying pan over medium heat. Add the leek and cook, stirring often, for 5 minutes or until soft but not browned. Add the flour and stir until well combined. Cook, stirring, for 1 minute. Remove from heat. Gradually stir in the milk. Return to medium heat. Cook, stirring with a wooden spoon, for 5 minutes or until the sauce boils and thickens.

Add the salmon, prawn, parsley, dill, mustard and lemon rind to the white sauce and stir until well combined.

Place half the boiled eggs into the base of a 7cm deep, 2.25L (9 cup) ovenproof dish. Spoon over half the seafood mixture. Top with remaining egg and seafood mixture. Spoon the devilled mash over the top. Smooth the surface. Use a fork to create lines in the top of the mash. Place the dish on a baking tray. Bake for 10 minutes or until a crust starts to form on the top. Brush the top with the melted butter and bake for a further 20-25 minutes or until golden.