Preheat oven to 450
Mix parsnips, chopped rosemary, garlic, and oil on a large rimmed baking sheet. Season with salt and pepper and toss to coat. Spread out in a single layer. Scatter chopped rosemary over. Roast for 10 minutes; turn parsnips and roast until parsnips are tender and browned in spots, 10–15 minutes longer. Season to taste with salt, pepper. Garnish with fresh rosemary sprigs.