A luxurious British classic: succulent salmon, smoked haddock, and plump king prawns in a creamy white wine and dill sauce, baked beneath buttery piped mashed potatoes and melted cheddar.
Boil potatoes in salted water for 15-20 minutes until tender; drain well, mash thoroughly with 25g butter, double cream, nutmeg, salt, and pepper until smooth and velvety.
Melt 25g butter in a saucepan, whisk in flour, and cook for 1-2 minutes. Gradually whisk in milk and white wine; simmer for 5 minutes until thickened. Stir in Dijon mustard, dill, parsley, and garden peas.
Arrange salmon cubes, smoked haddock cubes, and king prawns in an even layer across the base of a deep baking dish; pour creamy herb sauce over seafood.
Pipe or spread mashed potato evenly over the filling, rough up surface with a fork, and scatter grated mature Cheddar over top.
Bake in a preheated oven at 200°C (180°C fan) for 30-35 minutes until bubbling around the edges and golden-crisp on top.