Heat the butter in a 5-quart stock pot or Dutch oven. Add the carrots and onion and cook the vegetables together for 5 minutes. Add the salt, fresh ginger, chicken stock and orange juice and bring the mixture to a simmer. Continue to simmer over low heat for 40 minutes, stirring occasionally.
Add a pinch of nutmeg, ¼ cup of the heavy cream and orange zest. Season to taste with white pepper.