Updated Nov 24, 2014Chatelaine
- Peel potatoes. Slice into quarters. Place in a large pot. Cover with water. Bring to a boil over high heat. Reduce heat. Simmer, covered, until very tender, 25 min. Drain.
- Meanwhile, thinly slice onions and grate parmesan. Just before potatoes are done, place cream, butter and Dijon in a bowl. Heat in the microwave or in a small saucepan on the stove.
- Place drained potatoes back in pan. Mash until really smooth. Stir cream mixture, then pour into potatoes. Add onions and grated parmesan. Stir to evenly mix. Taste and add salt and more grated parmesan, if you like. If making ahead, cover and refrigerate up to 2 days. To reheat, turn into an 8-in. (2-L) baking dish. Cover potatoes with foil and bake in a 350F (180C) preheated oven until hot, about 40 min. Or loosely cover and microwave on medium-high until hot, from 8 to 10 min. Stir halfway through.