Preheat oven to 425°F. Line 2 large rimmed baking sheets with foil and spray liberally with cooking spray. Set aside.
Scrub potatoes, peeling is optional. Cut into approximately ¼ inch strips. Place into a large bowl and soak in cold water for at least 30 minutes up to 4 hours. Drain well and pat dry.
Place into a large plastic storage bag, drizzle with olive oil. Seal bag and toss with oil until coated.
In a small bowl, whisk together cornstarch, chili powder, sugar, salt, garlic powder. onion powder, cumin and cinnamon. Add to potatoes, seal bag and shake until evenly coated.
Dump sweet potatoes onto pans spreading into a single layer. Bake for 30-40 minutes until golden and tender. Turn once, halfway through.
Serve immediately with comeback sauce or your favorite aioli for dipping.