Pierce the sweet potatoes a few times with a fork and place them on a baking sheet. Bake for 40–50 minutes, or until fork-tender.
Let the potatoes cool slightly, then slice each one in half lengthwise. Carefully scoop out a little of the flesh, leaving a thin layer inside to help the skins hold their shape.
Brush the potato skins lightly with olive oil and place them cut-side up on the baking sheet. Bake for another 10 minutes until slightly crisp.