Preheat the oven to 400 degrees F. Coat a large baking sheet with cooking spray.
Arrange the wonton wrappers on the sheet and spray them with cooking spray. Sprinkle them evenly with the granulated sugar, and then bake until golden brown, about 5 minutes.
Remove from the oven and arrange 4 of the wontons on a serving platter or individual dessert dishes. Top each one with 2 tablespoons of the whipped topping and then one-eighth of the mandarin sections. Top each with a second wonton wrapper. Repeat the layers (whipped topping, mandarin oranges, wonton wrapper). Sift the confectioners' sugar over the top layer and serve.