Melt 4 tablespoons butter in large pot over medium heat. Add green onions and shallot and cook 3 minutes. Add 1 cup chopped fresh cilantro and next 6 ingredients. Increase heat to high; bring mixture to boil. Add clams and cover pot. Cook until clams open, shaking pot often, about 7 minutes. Using slotted spoon, transfer clams to 6 soup bowls (discard any clams that do not open). Boil remaining liquid over high heat until slightly thickened, about 1 minute. Whisk in remaining 1 tablespoon butter. Season with salt and pepper. Pour sauce over clams. Sprinkle with remaining 1/4 cup chopped cilantro and serve.