Add butter and melt. Add onions and cook until translucent and soft. add celery, parsley, veggie blend, Old Bay, white pepper, and white wine. Bring to a boil, and cook for one minute. Add seafood stock and potatoes. Simmer for 12 minutes or until potatoes are soft and stock begin to thicken slightly. Lower heat and add rinsed cod. Cook for about 10 minutes and gently stir once. Lower heat to lowest setting and add heavy cream. Allow to stay warm for at least one hour before serving.