Place saffron threads in a small heatproof bowl. Add 2 tbsp of warm fish stock and set aside for 10 minutes until the liquid turns deep orange.

Melt butter in a 5-quart heavy-bottomed saucepan over medium heat. Add leeks and cook for 5 minutes, stirring occasionally, until softened and glossy but not browned.

Add minced garlic and cook for 1 minute until fragrant.

Add potato cubes, remaining fish stock, bloomed saffron with its liquid, and the bay leaf. Stir to combine and bring to a gentle simmer.

Simmer uncovered for 12 to 14 minutes, stirring occasionally, until potatoes are just tender when pierced with a knife tip.

Nestle the smoked haddock pieces into the simmering broth in a single layer. Reduce heat to low and cook for 5 to 7 minutes until the fish turns opaque and flakes easily when pressed.

Use a spoon to gently break the fish into large flakes directly in the pot. Remove and discard the bay leaf.

Remove the pot from heat. Pour in the double cream and stir slowly until fully incorporated and the broth looks uniform and golden.

Taste the chowder and add salt and black pepper as needed. Smoked haddock releases brine as it cooks, so the chowder may need very little extra salt.

Ladle into deep bowls and scatter chopped parsley or chives over each portion. Serve immediately with crusty bread.