Heat a large dutch oven or stock pot over medium heat and add butter.   Add the onion to the pan and saute for 5-10 minutes or until softened. Add the garlic and saute for 1 more minute.

Add the white wine, potatoes, thyme, and bay leaf & bring to a simmer.  Add the fish stock, bring back up to a simmer, and cover, until potatoes are almost fork-tender, about 20 minutes.

Add the cod & seafood, and cover.  Turn up the heat to return to simmer if necessary.  Cook until the mussels have opened and the cod begins to flake apart, about 10-15 minutes.

Remove the lid and add the fresh herbs.  Season to taste with salt and pepper.   Add a spoonful of heavy cream to each bowl as serving, and serve with plenty of bread.