Preheat your oven to 425°F (220°C) and line a baking tray with parchment paper.
In a large bowl, combine the cubed sweet potatoes, olive oil, garlic powder, oregano, thyme, salt, and pepper. Toss well to coat all the sweet potato pieces evenly.
Spread the sweet potatoes out in a single layer on the prepared baking tray.
Roast in the oven for 20 minutes, then remove and sprinkle the grated Parmesan cheese over the top.
Return the tray to the oven and roast for an additional 10-15 minutes, or until the sweet potatoes are golden brown and tender.
Remove from the oven and let cool for a couple of minutes.