This recipe calls for glycerin, which helps keep the fondant soft and supple. You can find it in some cake stores, some pharmacies, or on many web pages. Be sure to get food-grade or food-safe glycerin.
1 tbsp (1 envelope, or 1/4 oz) unflavored gelatin
1/4 cup cold water
1/2 cup light corn syrup
1 tbsp glycerin
1 tbsp clear flavoring of your choice (to keep the fondant white)
2 lbs powdered sugar
1. Place the cold water in a small microwave-safe bowl and sprinkle the gelatin on top, stirring it to distribute it. Let the gelatin set and soften for two minutes. Once set, microwave the gelatin for 15 seconds until it liquefies, but do not let it boil.
2. Once liquid, stir the corn syrup, glycerin, and any flavorings you might want into the gelatin. Microwave for an additional 15 seconds, then stir again until the mixture is smooth and clear.
3. Place 1.5 pounds of the powdered sugar in the bowl of a large stand mixer fitted with the paddle attachment and make a well in the center. Pour the melted gelatin mixture over the corn syrup into the well.
4. Begin to mix the candy on low speed until the liquid is incorporated. You will have a very sticky mess! With the mixer running, gradually add the rest of the powdered sugar. The candy will get stiffer and you will need to scrape down the sides of the bowl to ensure all of the sugar is incorporated.
5. At this point the fondant will be stiff, but still very sticky. That's normal. Wrap it tightly in cling-wrap and let it sit at room temperature for 24 hours to ripen.
6. After 24 hours, you can unwrap the fondant and knead it until smooth. It is now ready to roll. When you roll it, make sure your workstation and rolling pin is dusted well with powdered sugar or cornstarch. If you are using it to cover a cake, check out this photo tutorial showing how to cover a cake with fondant. Unused fondant can be wrapped tightly in cling-wrap and stored at room temperature for several weeks. Knead well before using.