Preheat oven to 190C/Gas 5.
1) Grease a 20 by 30-cm baking tin with 15g of butter.
3) Cut each of the yams into 8 evenly shaped wedges. Lay them out in the prepared baking dish in an even layer. Melt the butter in a small saucepan over medium heat. Stir in the brown sugar and allow to dissolve. Mix in syrup and cook until smooth. Pour the glaze over the yams and sprinkle with nutmeg.
3) Cover the baking tin with foil and bake for about 45 minutes or until the yams are tender when pierced with a fork but they still hold their shape.