Preheat the oven to 400 degrees F. Coat a large, rimmed baking sheet with cooking spray.
In a large bowl, combine the potatoes and olive oil and toss to coat. In a medium bowl, mix together the Parmesan, parsley, salt, pepper, garlic powder and cayenne until fully combined.
Sprinkle the parsley mixture on the potatoes and gently toss to evenly coat. Transfer to the prepared baking sheet and bake the potatoes, flipping them with a spatula every 10 minutes to prevent sticking, until golden brown, about 45 minutes. Season with salt and pepper to taste. Serve hot.