01 - Preheat the oven to 430°F. Line a large baking tray with parchment paper or lightly oil it.
02 - Place peeled and cut parsnips in a large bowl. Drizzle with olive oil, then season with sea salt, black pepper, and dried thyme or rosemary if using. Toss thoroughly to coat evenly.
03 - Spread the parsnips in a single layer on the prepared baking tray, ensuring they are not crowded.
04 - Roast the parsnips for 20 minutes.
05 - Turn each parsnip baton to promote even browning.
06 - Return the tray to the oven and roast for an additional 15 minutes, or until parsnips are golden brown with crisp edges and tender interior.
07 - If desired, immediately sprinkle grated Parmesan over the hot parsnips. Garnish with chopped fresh parsley before serving.