Sweet potato is generally associated with southern foodways; the cultivation of the tuber in Virginia dates to the early 1700s, if not before then, and for nearly three hundred years it has continued to appear in a wide variety of southern dishes. The sweet potato, however, originated in the tropical New World and, thanks to Christopher Columbus, was being cultivated in Spain by the end of the fifteenth century and in England by the mid-sixteenth century. The tuber, therefore, was familiar to colonial Americans before they ever arrived in the New World, and dishes like sweet potatoes and apples refer directly to traditional British foodways.
Preheat the oven to 325°F. Fill a Dutch oven with lightly salted water and bring to a boil over high heat. Add the sweet potatoes and cook for 15 to 20 minutes, until just fork-tender. Drain the potatoes and set them aside until they are cool enough to handle. Peel and cut the potatoes into 1/4 inch thick slices. Spray a large baking dish with non-stick cooking spray and place half of the potato slices in the bottom of the dish. Top with half of the apple slices. Sprinkle with half of the brown sugar, margarine, and mace. Season to taste with pepper. Repeat with alternate layers of the remaining potato slices, apple slices, sugar substitute, margarine, and mace. Bake for about 1 hour, until the top is brown and the liquid has evaporated. Serves 16 (approximately 1/3 cup per serving)