Sweat the onion: In a medium flameproof casserole over medium heat, melt the butter. Add the onion to the pot and let it sweat for about 8 minutes, until soft but not browned at all (this is a white stew, you don’t want the onion to take on any colour).
Next, cook the coddle. Once the onion is translucent add the bacon and continue to cook over a low heat until the bacon is pale pink and a few tablespoons of the fat have been rendered, about 10 minutes. Add the potatoes, sausage, chicken stock, cream and bay leaves. Raise the heat to medium-high and bring liquid to a boil. Lower the heat to medium and cook slowly until the potatoes are cooked through, about 30 minutes.
Add the herbs and serve/ Remove the coddle from the heat, stir in the parsley and thyme and serve immediately with lots of crusty bread. If you wish, sprinkle a little bit of cracked black pepper on top. The coddle can be made a day ahead and gently reheated on the stove or in a 150°C/3gas mark 2 oven for 30 minutes.
