Corn Chex™ cereal and freeze-dried berries give this no-bake treat bars fun, Fourth of July flair. Directions 1 Spray 8-inch square pan with cooking spray; line with cooking parchment paper, leaving an overhang of paper on two sides. 2 In 4-quart saucepan, heat butter and marshmallows over medium heat, stirring frequently, until melted and smooth.