Heat the oven to 425°F with a large rimmed sheet pan inside for 8 to 10 minutes.
Scrub and dry the squash. Trim the ends, halve lengthwise, scrape out seeds, and cut crosswise into uniform 1/2-inch half-moons.
Whisk olive oil, maple syrup, Dijon, salt, pepper and thyme, then toss with the squash until both cut sides are lightly coated.
Spread the half-moons on the hot pan without overlap. Roast for 14 minutes without moving them.
Flip each piece and roast 10 to 15 minutes more until both sides are browned and the flesh is tender.
Rest for 5 minutes, drizzle with cider vinegar and add pepitas just before serving.
