2 pounds celery root
1/2 cup milk or cream
3 tablespoons unsalted butter
Salt to taste
Chopped celery root leaves, for garnish (optional)
1 Bring a large pot of salted water to a simmer (1 Tbsp of salt for every 2 quarts of water).
2 While the water is coming to a boil, peel the celery roots with a knife. Cut the celery roots into 1-inch pieces.Boil for 25-30 minutes, until soft.
3 Drain the pot, steam the celery root: Drain the pot, return the celery roots to the pot to the stovetop on low. Cover and let the celery roots steam for a minute or to, shaking the pan a bit to prevent sticking.
4 Add the milk or cream, butter and a generous pinch of salt and mash with a potato masher until it is as smooth as you like it. Add salt to taste and garnish with the celery root leaves, if using.
Source: "Simply Recipes" https://www.simplyrecipes.com/recipes/celery_root_mash/