Place a rack in the center of the oven and preheat oven to 425 degrees. Line two baking sheets with parchment paper or aluminum foil and spray with nonstick cooking spray.
In a small bowl, whisk together cornstarch, chili powder, red pepper flakes, garlic powder, cumin and ancho chili powder. Set aside.
Rinse potatoes and peel with a vegetable peeler. You can leave some skin bits on the potatoes if you want to go for a more rustic fry. Using a sharp knife, slice a 1/4-inch piece off the potato lengthwise. The flat edge will give you a stable base to slice on. Rest the potato, cut side down, and slice potato into 1/4 to 3/8-inch planks.
Stack planks in piles 2 to 3 planks high, and slice lengthwise into 1/4 to 3/8-inch strips.
In a medium bowl, toss the potato strips with olive oil, Worcestershire sauce and grill seasoning. Sprinkle the cornstarch mixture over the potato slices and use tongs or forks to toss together, making sure that every potato is coated with a bit of cornstarch and seasoning.
Spread potatoes in a single layer across the prepared baking sheets. Bake for 30 to 40 minutes, removing the potatoes from the oven 2 or 3 times during baking to toss them together. Cook until potatoes are cooked through and brought to your desired crispiness. Remove from the oven, top with cheese and return to the oven for just a few minutes to melt the cheese. Remove and place onto a platter. Sprinkle with green onions and serve immediately.