I recommend the book Veg by the Hugh Fearnley-Whittingstall
We had his Sweet Potato and Peanut Gratin last week for the first time and it was delish.
INGREDIENTS
Serves 4-6
2 lb sweet potato
*2 tbsp sunflower oil
1 fresh red chilli, seeded and finely chopped
3 cloves garlic, finely chopped
**1 cup double cream (subbed it with low fat cream cheese)
sea salt and freshly ground pepper
1/2 cup crunch peanut butter (only had cashew nut butter)
finely grated zest of 1 lime, plus about 2 tsp juice
METHOD
Preheat oven to 375°F and lightly oil a large gratin dish. Peel the sweet potatoes and cut them into slices a bit thinner than 1/8 inch. In a large bowl, toss the potato slices with 1 tablespoon of the oil, the chile, garlic, cream, and some salt & pepper.
Arrange half the sweet potato slices evenly in the gratin dish. You do not have to layer them piece by piece, but try to ensure that the slices are mostly lying flat.
Beat the peanut butter with the remaining 1 tablespoon of oil, the lime zest, and the lime juice. Spread this mixture in dollops over the sweet potatoes in the dish. Cover evenly with the remaining sweet potato slices. Pour over any cream remaining in the bowl.
Cover the dish with foil and bake for about 20 minutes, then remove the foil. Bake for a further 30 minutes or so, until the sweet potatoes are completely tender and the top is browned and crisp. For extra crispness, you can finish under the broiler for a couple of minutes, but watch carefully. Serve hot, with a crisp, leafy salad to balance the sweet richness of the gratin.