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How to Harden Marshmallow Fondant
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5 from 1 vote

How To Harden Marshmallow Fondant

Do you struggle with your marshmallow fondant being too soft? Do your designs not hold their shape? If so, you will want to know how to harden marshmallow fondant.
Course: Dessert
Cuisine: American
Keyword: How To Harden Marshmallow Fondant
Author: cakedecorist.com



  • 1 package white mini marshmallows 16 ounces
  • 2-5 tablespoons water
  • 2 pounds approximately 8 cups powdered sugar, sifted
  • 1/2 cup solid vegetable shortening
  • 1/2-1 teaspoon CMC or Tylose


  • Microwave the Marshmallows and Water - In a microwave-safe bowl, add the marshmallows and two teaspoons of water. Microwave in 30 seconds intervals, stirring after each time. Continue microwaving until melted, which will be approximately 2-2 1/2 minutes.
  • Add in Powdered Sugar - Add 3/4 of the powdered sugar to the melted marshmallows in a large bowl. Carefully fold the powdered sugar into the marshmallows using a wooden spoon. Add in 1/2-1 a teaspoon of CMC or Tylose (helps the fondant so it hardens up).
  • Knead the Fondant - Generously grease a clean working space in your kitchen with shortening. Cover your hands in shortening and turn the marshmallow fondant onto your work surface. Knead it as you would dough, adding the additional powdered sugar as you go.
  • If the fondant begins to tear, add in more water. Continue to knead for several minutes until it is smooth and flexible.
  • Roll Out Fondant - Roll out the fondant into thin sheets. Rolling it out thin will help it harden quicker.
  • Grease plastic wrap with vegetable shortening and cover the fondant with it then place in an airtight container. Let the fondant sit overnight, or up to a week, at room temperature before using.
  • By allowing it to sit at least overnight, the texture will firm up. This will make it easier to use than if you were to use it right after making it.
  • Add Fondant to Cake - Add the rolled fondant to your cake, smoothing it out as you go. If it is still too soft, use a fan or blow dryer to help harden it. Trim off any excess fondant from your cake.


Adding CMC, also known as Tylose, to fondant is a great way to help harden to make it easier to work with. Tylose is a type of powder that improves the strength and elasticity of fondant. It helps fondant harden up, which is great if you are making designs such as flowers and decorative figures.
Any leftover fondant can be left in sheets or rolled into a ball or log. Wrap the leftovers in plastic wrap that has a layer of shortening on it, as this will help keep it fresh. Then, place it in a Ziploc bag or an airtight container.
When properly stored, fondant can last for 1-2 months. Cakes that have been decorated with fondant can last for 3-4 days at room temperature, covered in an airtight container. It is typically best to avoid putting your fondant in the fridge or freezer.
Since fondant is prone to picking up dirt and lint, be sure your work surface was cleaned prior. Also, make sure to wash your hands right before starting. It is best to avoid wearing sweaters when working with fondant, as lint from sweaters can easily get stuck in it.
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