Preheat the oven - Heat the oven to 425℉. Pour 1 tablespoon olive oil into a large cast-iron skillet, swirl it so it coats the whole pan, then put it in the oven while you cut the potatoes.
Mise en place - Scrub and trim any blemishes off of the sweet potatoes, then make ⅛-inch slices across the potato on a slight bias from the top to the bottom of the potato, cutting almost all of the way through the potato, stopping before you reach the bottom.
Par-bake the sweet potatoes - Carefully remove the skillet from the oven and nestle the sweet potatoes inside. Drizzle the top of each potato with ½ teaspoon olive oil, sprinkle with salt, then bake for 30 minutes.
Infuse the butter - While the sweet potatoes are baking, add the butter to a small pan with 1 teaspoon salt. Using a rasp, grate the garlic into the pan, then heat over low until the butter is melted, swirling occasionally.
Butter the sweet potatoes - Take the sweet potatoes out of the oven, and carefully (gently!) pry the slices apart. Use a brush to generously coat the potatoes with garlic butter so that the butter seeps into and around the slices. Reserve a tablespoon of the infused butter.
Bake and finish - Bake for an additional 10 minutes. Brush with reserved garlic butter, garnish with your favorite toppings, and serve with any condiments of your choosing.