Simply clean them thoroughly, cut off the tips and stems, then cut into bite size chunks. Toss with olive oil, salt, and pepper–bake at 400 until they are soft, stirring once or twice.
This is also my favorite way to eat sweet potatoes. Ironically, I hate sweet potatoes or yams drenched in sugar and/or marshmallows. But prepared this way the sweet flavor shines through. YUM!