4 lbs. sweet potatoes, peeled and cut into chunks
2 1/2 c. unsweetened apple cider (natural unsweetened and unfiltered is preferable to bottled cider or apple juice)
1/2 c. dark brown sugar
8 tbsp. (1 stick) unsalted butter
2 inch piece cinnamon stick

In a large non-corrodible saucepan, put the potatoes, cider, brown sugar, 6 tablespoons of the butter, and the cinnamon stick. Bring to boil over moderate heat. Reduce the heat to a simmer. Partially cover and cook, stirring occasionally, until the potatoes are very tender (about 45 minutes). Let cool slightly. Remove the cinnamon stick and force the potatoes through the medium disk of a food mill or puree in batches in a food processor.

Transfer to an oven-proof serving dish. THE POTATOES MAY BE PREPARED TO THIS POINT SEVERAL DAYS IN ADVANCE OF SERVING! Cover tightly and refrigerate. Return to room temperature before proceeding. Preheat oven to 325 degrees. Dot the surface of the potatoes with 2 tablespoons of butter. Cover tightly with foil and bake, stirring once or twice, until steaming (about 20 minutes). Remove foil and bake 5 minutes longer. Serves about 8.