Using celeriac with the potatoes makes a nice change from just mashed spud. A perfect fall recipe, the combination of the celeriac, potato and mushrooms makes this recipe an ideal accompaniment for all sorts of roast and braised meats.

Cook celeriac and garlic in a large saucepan of boiling salted water for 15 minutes. Add potato and boil until the celeriac and potato are very tender, about 20 minutes longer. Drain.

Return to the same saucepan and stir over medium-high heat until any excess liquid in pan evaporates, for about 2 minutes. Add cream and butter. Mash until mixture is almost smooth. Season to taste with salt, pepper, nutmeg and add the chives. Serve with the mushrooms on the top.

In the meantime, clean the mushrooms and cook on medium heat in olive oil, with salt, pepper and parsley. Reserve for garnish when they are cooked.

Notes: Celeriac, or celery root, a variety of celery, originated in the Mediterranean and was used by agronomists during the Italian Renaissance. While it is a popular vegetable in Europe, it is not as well-known in North America. Celeriac is generally the same size as a turnip. Its brown, rough skin is thick and mottled. This root vegetable has creamy white flesh with a crisp texture and an intense celery flavor.