Preheat oven to 350 degrees.
Cut sweet potatoes into large chunks or cubes. In a large bowl, toss pieces with olive oil. Set aside.
In a smaller bowl, mix salt, sugar, brown sugar, garlic, onion, paprika, chili powder, pepper, cayenne pepper, thyme, cumin, nutmeg and cinnamon.
Toss sweet potato cubes with the rub. Place in a large baking pan and cover with foil. Bake one hour or until done.
This recipe is adapted from Dr. BBQ's Big-Time Barbecue Cookbook