A Japanese or French mandoline is great for slicing vegetables uniformly - anywhere from very thin to thick - and takes much less time than slicing by hand with a knife.
Preheat the oven to 400F, and place the rack in the middle of the oven. In a medium bowl, combine the potatoes, olive oil, and thyme. Season with salt and pepper, and toss until well coated.
Generously brush a large rimmed baking sheet with olive oil, and overlap the potato slices just slightly. Bake until the potatoes are golden brown and crisp in places, about 30 minutes.