Preheat oven to 400°F (200°C).
Wash sweet potatoes and scrub clean. Pat dry.
Pierce each potato 3 to 4 times with a fork.
Rub lightly with olive oil.
Sprinkle with salt and pepper if desired.
Place directly on oven rack. Put baking sheet on rack below to catch drips.
Roast 45 to 60 minutes depending on size.
Check at 45 minutes. Fork should slide in easily.
Continue cooking if needed, checking every 5 minutes.
Remove when tender. Cool 5 minutes.
Slice open lengthwise. Fluff with fork. Add toppings. Serve hot.