Position an oven rack on a lower-middle rung; heat the oven to 450°F. Cut the parsnips into matchsticks 2 inches long and a scant 1/2 inch thick, discarding any woody core. Dump the matchsticks onto a rimmed baking sheet large enough to fit them in a single layer. Sprinkle the olive oil, cayenne, and salt over all; toss to mix and coat well. Roast for 15 min., stirring once or twice. Sprinkle with the garlic, stir well, and continue roasting until the parsnips are well browned, about another 15 min. Let cool slightly, taste for salt, and serve.
nutrition information (per serving):