Bring a large pot of salted water to a boil over high heat. Add the potatoes and celery root and cook until tender, about 15 minutes. Drain and return to the pot.
Add the butter, milk, salt, and pepper and mash until smooth. Serve warm.
Interesting Facts
Celery root, also known as celeriac, is a type of root vegetable that has a mild, celery-like flavor.
Mashed potatoes and celery root is a great side dish for pork or beef.
This dish can also be served as a main course with a salad or vegetables.