Preheat the oven to 400 F
Thinly slice the potatoes and add them to a large bowl.
Toss them together with the olive oil, salt, pepper and garlic powder until evenly combined.
Spray a large baking dish with cooking spray, mine was about 11u0022 x 7u0022 but you can use a 9u0022 x 13u0022 or a large round dish.
Layer the potatoes in the baking dish so they overlap eachother to form three rows. If you're left with a few extra slices at the end just stick them in between the other slices until the pan is filled.
Pour the melted butter over the potatoes and throw on a few fresh pieces of thyme
Cover the pan with tinfoil. Bake for 30 minutes, until the potatoes are tender. Remove the tinfoil and bake for an additional 35-40 minutes. Towards the last 10 minutes, I like to raise the heat to 425 F.
Once the potatoes are done, top with flakey sea salt and a few extra pieces of thyme.