Preheat oven to 400ᵒ F.
Place fresh yams in a pot with 2 inches of water. Bring to a boil, reduce heat and simmer covered for 20 minutes or until yams are tender. Drain and cool, then peel.
Cut cooked or canned yams into chunks. Place in a large bowl. In a small bowl, stir together marmalade, syrup, cinnamon, and nutmeg. Pour over yams and toss to coat.
Turn into a 9 x 13-inch greased baking dish or similar-sized casserole. Dot with dairy or vegan butter.
Bake uncovered for 30 minutes, basting 2 or 3 times during cooking. Turn off heat and leave yams in oven for 10 more minutes before serving.