Preheat oven 375 degrees. Melt the butter and add the oil. Set aside.
Peel the potatoes and slice them thinly but keep them together. Grease a baking dish with some of the butter oil mixture. Place the potatoes horizontal in the dish. Wedge the shallots throughout the potato slices. Season with salt and pepper.
Pour the remaining butter oil over potatoes. Sprinkle with bacon and thyme leaves. Bake about 30 minutes.