How to Make It
Preheat the oven to 400°. Spread the sweet potato chunks in two 9-by-13-inch baking dishes. Add 1 cup of water to each dish, cover with foil and bake for about 25 minutes, until the sweet potatoes are barely tender. Pour off any remaining water from the baking dishes.
In a small saucepan, combine the brown sugar with the butter, five-spice powder and nutmeg and cook over moderate heat until the butter is melted and the mixture is bubbling, about 4 minutes. Pour the mixture over the potatoes, stir to coat and season with salt. Bake for about 10 minutes, basting a few times, until the potatoes are tender and nicely glazed. Sprinkle the walnut toffee over the potatoes and serve.