Preheat your oven to 400 degrees F and line a baking sheet with either parchment paper or a silicone baking mat. Set aside.
Bring a large pot of water to a boil. Once boiling, add the potatoes and cook for 6-9 minutes – you only want to parboil them. (You can test for doneness by checking that the center is no longer hard and the potato's color is even.)
While the potatoes cook, mince the garlic. In a small bowl, stir together the parmesan, olive oil, garlic, salt, pepper, garlic powder, and dried oregano.
Drain the potatoes and let them sit in the colander until just cool enough to handle. Then cut the potatoes in half and add them to a gallon-size food storage bag or a large bowl.
Add the cornstarch to the potatoes, close the bag and shake to coat them (or stir in the bowl until coated). Pour the parmesan mixture into the bag and shake to coat again.
Spread the potatoes out on the prepared baking sheet in an even layer. Bake for 25-30 minutes, flipping the potatoes halfway through the cooking time
Remove the potatoes from the oven and top with chopped parsley if desired. Serve warm.
Notes
You can store leftovers in the fridge in an airtight container for up to 4 days.
To reheat the potatoes, pop them into the microwave for a couple of minutes, or air fry them at 400 degrees F for 5 minutes until crispy.