Preheat the oven to 400°F (200°C).
Wash the delicata squashes under running water to remove any dirt.
Using a knife, cut the squashes in half lengthwise and scoop out the seeds with a spoon.
Slice the squash halves into 1/2-inch thick half-moons.
In a mixing bowl, toss the sliced squash with olive oil, salt, black pepper, and ground cinnamon (if using) until well coated.
Line a baking sheet with parchment paper for easy cleanup. Spread the seasoned squash in a single layer on the baking sheet.
Roast in the preheated oven for 25 minutes, turning halfway through, until the edges are golden brown and the squash is tender.
If desired, drizzle with maple syrup during the last 5 minutes of roasting for added sweetness.
Remove from the oven and serve warm.