I just watched Barefoot Contessa and Ina made this wonderful recipe that I think would be very good for our Christmas Eve dinner with the family. From her Barefoot Contessa Back to Basics Thanksgiving Countdown 2008 show on Food Network.
In a shallow pot or large saute pan over medium heat melt butter. Saute the fennel, celery root, potatoes, and apples with the 1 1/2 teaspoons of salt and 1/2 teaspoon of pepper, stirring occasionally, until the vegetables begin to soften or about 4 to 5 minutes. Add the cider and cover the pot tightly with a lid. Over low heat simmer for 30 to 40 minutes, stirring occasionally, until the vegetables are tender. If the vegetables seem to dry add a few more tablespoons of apple cider or water.
When the vegetables are cooked stir in the cream and cook for 1 minute. Using a food mill fitted with the coarsest blade process vegetable mixture. A food processor can also be used but will result in a smoother texture.
Taste and season with salt and pepper if needed than return to pot to keep warm until serving.