Preheat the oven to 400 degrees and lightly spray a shallow baking dish with cooking spray.
Melt the butter and stir in the olive oil and garlic. Set aside.
Thinly slice the potatoes using a mandoline or food processor. Arrange the slices vertically and pour over the butter mixture. Generously season with salt and pepper and place a few sprigs of thyme over top.
Place the dish on a baking tray and cover loosely with foil. Bake for 60 minutes or until golden brown and crispy on the edges.
Recipe by Friday is Cake Night at https://www.fridaycakenight.com/2016/02/crispy-roasted-potatoes/