Heat the oven to Gas Mark 5. Scrub the potaotes and dry, DO NOT peel, cut into thin slices. Melt the butter and add to the oil, use a little to brush onto an ovenproof dish, use the rest to bush onto the potatoes, layer the potatoes in the dish and add the garlic, salt and pepper and finally sprinkle over the thyme. Bake for 30-40 minutes, until the potatoes are tender and brown. These go with any meat, I add dried mint instead of thyme if I'm serving lamb, but I'm sure you could use other dried herbs also.