Put the cut sweet potatoes, cut side up, in the baking dish and drizzle with the olive oil. Place the unpeeled garlic cloves in a little foil, drizzle with olive oil and seal the foil packet, place it in the corner of the 9x13 dish.
Roast for 35 minutes, flipping the potatoes half way thru the cooking.
Make sure your potatoes are fully cooked by piercing with a fork, it should slide in without any resistance.
If they need to bake longer, remove the garlic and bake the potatoes an additional 5 minutes.