Preheat oven to 400^. Boil yams with jackets on about 15 minutes or until almost tender. Drain and cool. Butter an 11x7-inch baking dish. Peel and slice yams. Place a layer of yams in the dish, then a layer of apples and sprinkle with some of the brown sugar. Continue layering until yams and apples are used up. Sprinkle with almonds. Arrange mandarin oranges on top. Drizzle butter over top and pour the liqueur over top. Bake for 35 minutes.