In a large heavy saucepan, melt 1 TBSP unsalted butter. Add onions. Cook over medium high heat until translucent. Add in another TBSP of butter, corn and garlic. Add in corn. Saute another 4 minutes until corn is cooked through.
Pour the wine into the pan and reduce, scraping off any bits on the bottom of the pan. Lower heat. Add the clam juice, chicken broth and seasonings- thyme, salt, pepper, cayenne and Old Bay. Stir in the potatoes. Cover and cook 7-8 minutes until the potatoes become tender.
Add in cream and heat through- about another 5 minutes.
Finally, add in the fish and shrimp. Cook until just opaque through- about 3 minutes. Do not overcook the shrimp- it will become tough. Stir in the milk and heat until the chowder is piping hot.
Ladle into individual bowls and garnish with chopped chives.