Heat butter in a 4-quart saucepan over medium-high heat. Add the carrots, onion, and potato and cook for five minutes or until the vegetables are tender-crisp.
Stir broth, ginger root, and black pepper in the saucepan and heat to a boil. Reduce heat to low; cover and cook 20 minutes or until the vegetables are tender.
Place 1/3 of the carrot mixture into a blender or food processor. Cover and blend until smooth; pour into a medium bowl. Repeat the process twice with the remaining carrot mixture. Return all of the purée to the saucepan. Cook over medium heat until hot. Garnish with parsley, if desired.