To make the chowder: Heat a tablespoon of the oil and a knob of butter in a large sauce pan over a medium heat and fry the leeks and garlic for about 3 minutes. Add the thyme sprigs, bay leaf and potatoes and cook for another minute or two. Pour in the stock. Bring to the boil. Cover, reduce to a simmer and cook for 8-10 minutes until the potatoes are almost cooked. The liquid should have thickened slightly. Scatter in the chilli flakes and season with a little salt and black pepper.
Cut the fresh and smoked haddock into 3 cm pieces. Season the haddock and prawns then add them to the sauce pan and gently press down into the broth so that the fish is only just submerged. Cover and simmer very gently for about 5 minutes or until the fish is cooked. You will know it is cooked when the haddock flakes easily. Timing will depend on the thickness of the fish.
To serve: Take the sauce pan off the heat and remove the thyme sprigs and bay leaves. Still off the heat, spoon in the crème fraîche and gently swirl around in the broth until it looks creamy. Add the chives and serve with brown soda bread.
