Arrange a rack in the middle of the oven, and preheat to 425°F. Peel the sweet potatoes and cut them into rounds, each about 1-inch thick.

Place the rounds on a rimmed baking sheet. Drizzle with the butter (or ghee or coconut oil), sprinkle with salt, and toss to coat. Make sure each round is flat on the baking sheet, ideally without touching so they can get all gooey and caramelized around the edges.

Roast for 20 minutes, flip each round over, then roast for 20 minutes more.