Preheat oven to 425ºF. Butter a 9x13 baking dish and set aside.
Using a mandolin or sharp knife, slice the potatoes into thin rounds. Lay one layer of potatoes on the bottom of the baking dish and sprinkle with garlic and thyme. Drizzle 1/3 of the butter and olive oil over. Salt and pepper to taste. Repeat with 2 more layers of potatoes, butter/olive oil and spices.
Bake for 30 minutes or until desired doneness. Serve hot.