Marshmallow Fondant definitely is an improvement on boxed fondant, both in taste and usability. Using only five ingredients, you can upgrade your cakes with this incredible fondant hack!
Make the fondant: Put the sifted powdered sugar in a large bowl. Prepare to use half in the marshmallow mixture.
In the bowl of a stand mixed fitted with a dough hook, add the vegetable shortening.
In a microwave-safe bowl, heat the marshmallows in the microwave on High in 30 second increments until they're fully melted, stirring with a spoon after each burst. This can take about 1½ minutes or so. You can also melt the marshmallows instead in a large saucepan over Medium-Low heat, stirring until they're fully melted.
Pour the water on top of the melted marshmallows to loosen from the bowl. Add the mixture to the vegetable shortening.
With the stand mixer running on its lowest setting, start adding in half the powdered sugar (1 pound, 454 grams), 1 cup (114 grams) at a time and mix for 2 minutes or until it looks smooth. Repeat until you've used half of the powdered sugar (about 4 cups (454 grams) total).
Pull the marshmallow mixture off the dough hook (putting vegetable shortening on your fingers helps), and add it into the large bowl with the remaining powdered sugar.
Soften the Wilton fondant in the microwave on High for 40 seconds, then add it to the marshmallow mixture. Knead everything together until it's all mostly incorporated (some powdered sugar may not get mixed in depending on your kitchen's environment).
Dust your work surface with a bit of powdered sugar, and smear your hands with shortening (to keep the fondant from sticking. Transferring the marshmallow fondant to the work surface, knead and pull it like taffy until it's stretchy and smooth. If there are rough spots or it's tearing, heat the fondant in the microwave for 30 to 40 seconds until it's hot. Keep pulling the fondant until it stretches without breaking.
To use: Roll out the warm, pliable fondant about ⅛-inch thick in a size larger than the cake you're covering. It's best for the cakes to be chilled before covering so the crumb coating is cold.
Storage instructions: Store the fondant in an airtight bag at room temperature. It will keep for months. To use again, reheat and knead the fondant well until it's stretchy before each use.
One batch of marshmallow fondant should cover a 10-inch, 8-inch, and 6-inch round cake layers if it's rolled out to ⅛-inch thick.
Notes
If using marshmallows containing gelatin is a problem (or if you keep Kosher), you can use commercially-made or homemade marshmallow creme (aka marshmallow fluff) with the same results.For light colored fondant, knead in the food color gel during the pulling stage. For bright or dark colored fondant, mix 1 tablespoon food color gel with 1 tablespoon of warm water (don't use too much coloring or the texture of the fondant can be ruined). Add the color in while mixing the marshmallow and shortening together.