Preheat oven to 180 degrees C. Grease a medium size baking dish.
Cook sweet potato till soft, drain well and mash. Mix in margarine, eggs and nutmeg. Season with salt and pepper.
Put a layer of the sweet potato mix into the baking dish. Sprinkle with the reduced fat cheese and some of pinenuts. Cover the layer with lasagne sheets. Repeat the layers and finish with layer of reduced fat cheese and pine nuts and sprinkle on half the parmesan.
Bake for 30 minutes or until pasta is cooked. Top with remainder of parmesan while still hot.