Melt the butter in a soup pot over medium heat. Add the onions and a pinch of salt and sautee until softened, about 5 minutes. Add the white wine and raise the heat to high to bring to a full boil. Let boil for 3 minutes.

Grate one of the potatoes and cut the remaining 4 potatoes into 1 inch chunks. Add both of them to the onions along with the clam juice, bay leaf, and Old Bay seasoning. The liquid should just cover the potatoes. If it doesn't add a little water or vegetable stock to cover. Bring to a boil over high heat, lower the heat to medium low and simmer until the grated potatoes disintegrate and thicken the broth and the potato chunks are just tender. Do not cook until the large potato pieces are completely soft because they will continue to cook as the fish cooks. While that simmers pour the heavy cream into a small saucepan. Place the saucepan over a medium flame and warm it just until steam rises from the top but do not let it simmer or boil.

Stir the cod into the potatoes and pour the heavy cream over the top. Lower the heat under the pot to medium low. Keep it on a low simmer (do not boil!) until the fish is cooked through and potatoes are completely tender. Remove the bay leaf and adjust with salt and pepper to taste. Stir in the fresh dill and let cool to a temperature that is comfortable for eating. This additional standing time improves the flavours as well!

Serve in bread bowls if desired.