Preheat oven to 400 degrees. Line two rimmed baking sheets with aluminum foil, and brush with oil.
Lay squash pieces on baking sheets. Season with salt and pepper; sprinkle squashes evenly with half the sugar. Roast until sugar has melted, about 5 minutes.
Remove baking sheets from oven. Using tongs, turn over pieces. Season with salt and pepper; sprinkle evenly with remaining sugar. Roast until tender, about 20 minutes.