- Bring a large pot of salted water to a boil. Add carrots, cover partially and simmer 5 minutes. Add parsnips and cover partially. Simmer until vegetables are very tender, about 15 minutes. Drain well.
- Return vegetables to saucepan and stir over medium heat until any excess moisture evaporates.
- Transfer to food processor. Add butter and process until smooth. Season with nutmeg, salt and pepper.
- Can be made 4 hours ahead. Re-warm over low heat, stirring often. Transfer to bowl. Serve.