Heat oven to 375F°. Toss together parsnips, oil and salt in a shallow roasting pan.
Roast until tender and golden brown, 20 to 25 min. Transfer to a serving platter.
In a small saucepan over medium heat, cook butter and sage until butter just begins to brown and sage is crisped, 2 to 3 min. Pour over parsnips and serve.
Notes
Use this sage butter on any roasted vegetable. It's even delicious on roasts and steak!