Place two racks in the top and bottom ⅓ of oven then preheat to 450 degrees. Place two baking sheets, one on each rack, in the oven to preheat along with it.

Scrub sweet potatoes under cool water then blot dry using a kitchen towel. Peel potatoes (if desired) then trim away blemishes using a paring knife. Cut potatoes in half then into quarters. Cut each quarter into ¼" matchsticks then place them in a large bowl.

Drizzle oil over sweet potato fries then toss until completely coated. Sprinkle fries evenly with salt, cornstarch and desired spices then toss until cornstarch is completely dissolved and there’s a thin film coating each fry.

Remove hot baking sheets from oven then coat with cooking spray. Divide sweet potato fries evenly between baking sheets, separating the fries as far apart as possible to ensure maximum crispiness. Bake for about 30 minutes, flipping the fries every 10 minutes. Remove from oven then serve nice and hot.