Preheat oven to 400°. Toss parsnips and oil on a rimmed baking sheet; season with salt and pepper. Roast parsnips, tossing occasionally, until tender and deep golden brown in spots, 35–40 minutes.
Meanwhile, heat chiles de árbol, butter, vinegar, and honey in a small saucepan over medium heat, stirring occasionally, until butter is melted.
Drizzle chile-honey butter over parsnips and toss to coat.