Preheat convection oven to 350°F or conventional oven to 400°F. Coat 3 half sheet pans or 1 full sheet pan and 1 half sheet pan with cooking spray.
Cut off ends of squash. Stand each on one flat end and cut in half lengthwise. Remove seeds and stringy flesh with a metal spoon. Place the squash halves cut side down on cutting board and cut into 1⁄4-inch slices (“smiles”).
Arrange the squash smiles on the prepared baking sheets. Brush with oil. Sprinkle with sugar, distributing as evenly as possible.
Bake until the sugar is just melted and the smiles are just golden, about 12 to 15 minutes in a convection oven or 20 minutes in a conventional oven.
