In Provence, a Tian is a type of earthenware roasting tray that is used for vegetable and gratin dishes of the same name. Once cooked, a Tian is generally left to cool before serving.
Preheat oven to 325°F. Chop parsnip and leek whites into more or less equal-sized pieces. Set leek greens aside for another use.
Place vegetables, spices and ½ the fat in a bowl. Salt and pepper. Mix well.
Scatter cabbage leaves around a Tian or roasting dish. Place vegetables on top and pour on remaining duck fat.
Place the roasting dish in the center rack of the oven. Roast until cooked to your liking, between 1¼-1½ hours.
Garnish with chives.
A variation of the Squash, Fennel and Celery Root Tian from The Spice Trekkers Cook at Home