Preheat your oven to 400°F (180°C fan-assisted).

In a pot, bring salted water to boil and add the peeled, chunked potatoes. Cook for approximately 15 minutes until completely tender. Drain, then mash with butter and milk, seasoning with salt and pepper. Set aside.

In a saucepan over medium heat, melt the butter. Add the chopped onion, diced carrot, and minced garlic. Sauté for about 5 minutes until softened.

Sprinkle in the curry powder and ground turmeric. Stir continuously for 1 minute.

Add the flour, stirring continuously for 1 minute to create a paste-like consistency.

Gradually whisk in the whole milk and stock, stirring until the sauce thickens and becomes smooth, about 4-5 minutes.

Add the white fish, smoked fish, and frozen peas to the sauce. Simmer gently for 3-4 minutes without boiling.

Remove from heat and gently fold in the cooked shrimp and chopped parsley. Season with salt and pepper.

Transfer the fish filling to a baking dish. Spread the mashed potato topping evenly across the surface.

Bake for 25 minutes, or until the potato topping turns golden and crispy. Allow to rest for 5 minutes before serving.