Mashed Potatoes and Celery Root

Serves 8 to 10.
Ingredients
- 2 large celery roots, about 2 lb. total, peeled and cut into slices 1 inch thick
- 2 1/2 lb. russet potatoes, peeled and cut into slices 1 inch thick
- Kosher salt, to taste
- 3/4 cup half-and-half
- 3 Tbs. unsalted butter
- Freshly ground white pepper, to taste
Directions
Put the celery roots and potatoes in separate large saucepans. Add water to cover and a large pinch of kosher salt to each pan. Bring both to a boil over high heat, reduce the heat to low, cover and simmer until the vegetables are tender, about 20 minutes. Just before they are done, place an ovenproof serving bowl in a 200°F oven. (There is no need to preheat the oven.)In a small saucepan over low heat, combine the half-and-half and 2 Tbs. of the butter and heat until the butter melts. Turn off the heat and cover to keep warm. Drain the potatoes and celery root, then return them to one of the large saucepans and set over medium-low heat; shake the pan until the vegetables begin to stick to the bottom. Remove from the heat.
Pass the vegetables through a ricer into the warmed serving bowl. Alternatively, pass the vegetables through a food mill, or mash them in the pan with a potato masher. Stir in the warm half-and-half mixture. Season with kosher salt and white pepper. Using a rubber spatula, scrape down the sides of the bowl and swirl the top of the puree. Top with the remaining 1 Tbs. butter and serve immediately. If necessary, keep warm in a 200°F oven for 15 to 20 minutes, or cover the bowl and set it in a pan of hot water.