For the caramel popcorn, make sure to pick a medium saucepot that has at least 5-inch-high sides, as the caramel mixture will bubble up as it cooks. If your candy thermometer doesn't quite reach the caramel mixture at first, don't worry: as the caramel boils, the bottom of the thermometer will reach the mixture. Powdered Cheddar cheese comes in two versions: classic orange or white Cheddar. Using the orange Cheddar is classic to Chicago, but you can easily substitute white Cheddar powder instead. You can find powdered Cheddar cheese in most grocery stores or online. For the cheese popcorn: Powdered cheddar cheese comes in two versions, classic orange or white cheddar. Using the orange cheddar is classic to Chicago but you can easily substitute white cheddar powder instead. You can find powdered cheddar cheese in most grocery stores or online.