Preheat the oven to 400℉. Prepare a baking sheet with non-stick spray.
Peel the parsnips and cut them into baton shapes.
Transfer the parsnips to the baking sheet. Drizzle with olive oil and sprinkle with salt and pepper. Toss to coat.
Roast the parsnips for 20 to 25 minutes until softened and starting to brown.
While the parsnips are roasting, prepare the cider reduction glaze.
Simmer the cider and brown sugar over high heat until reduced to 1/2 cup.
Whisk in the apple cider vinegar, butter, salt, and black pepper.
Remove the parsnips from the oven, then pour the cider reduction evenly over them.
Return to the oven for another 10 – 12 minutes until bubbling and sticky.
Serve the parsnips on a platter, drizzled with any remaining glaze.