Heat oven to 350 degrees. Place butter, granulated sugar and brown sugar in a large roasting pan; whisk until incorporated. Add parsnips; toss. Sprinkle with salt, pepper, and garlic powder; toss. Cover with foil; bake 20 minutes.
Remove foil; stir. Roast parsnips, uncovered, until lightly browned, about 20 minutes. Stir; adjust seasoning. Sprinkle with chives, and serve.