In large pot cook onion in butter over medium high heat. Add carrots and stock. Season with nutmeg, salt and pepper. Add rice and water. Simmer until carrots are soft and rice is done. Puree soup in half batches in a food processor or blender. Return to pot and season to taste. Return to a simmer for 10 minutes. Serve with scallions as a garnish.
Recipe Courtesy of Food Network Kitchens