Preparation / Directions:
1. Place the celery root and potato in a medium saucepan and cover with cold water. Season with salt and cook until soft, 15 to 20 minutes. Drain the water and return the celery and potato to the pan. Pour in the cream and simmer over medium heat, stirring occasionally to prevent sticking, until thickened and most of cream is absorbed, about 10 minutes.
2. Remove from the hear, stir in the butter, and season with salt and pepper to taste. Puree in a food mill, return to the pan, and keep warm over simmering water. Use as needed.
Makes about 2 1/2 cups