DIRECTIONS

1. Preheat oven to 400 degrees F. In 13″ by 9″ glass or ceramic baking dish, combine broth and margarine; place in oven while oven preheats to melt margarine.
2. Meanwhile, in large bowl, toss all potatoes, celery root, and parsnips with 1 1/4 teaspoons salt and 1/2 teaspoon pepper until well mixed.
3. Remove baking dish from oven; add vegetables and stir to coat with broth mixture. Cover dish with foil and bake vegetables 40 minutes.
4. Remove dish from oven. In 1-cup liquid measuring cup, heat cream in microwave oven on High 45 seconds. Pour cream evenly over vegetables; sprinkle with Gruyère. Bake, uncovered, about 30 minutes longer or until top is golden and vegetables are fork-tender. Let stand 10 minutes before serving.
5. Do Ahead: Prepare recipe up to 2 days ahead. Cool; cover with foil and refrigerate. When ready to serve, let stand at room temperature 30 minutes, then bake, covered, in preheated 325-degree oven for 30 minutes. Remove cover and bake 15 minutes longer or until hot.