Melt butter in heavy large saucepan over medium heat. Add carrots and onions. Cover saucepan and cook until vegetables begin to soften, stirring occasionally, about 15 minutes. Mix in ginger, orange peel and coriander. Add 2 cups stock. Reduce heat to medium-low. Cover pan and simmer soup until carrots are very tender, about 30 minutes. Puree soup in batches in processor or blender. Add remaining 3 cups stock and half and half to soup*Season with salt and pepper. (Can be prepared 1 day ahead. Cover and refrigerate.) Cook over medium heat until warm. Ladle into bowls. Sprinkle with parsley and serve.