Use meringue powder or cornstarch to prepare stiff buttercream frosting that holds its shape even in warm weather. Sweet and buttery in flavor, stiff buttercream frosting is ideal for decorating patterns and writing on cakes and cookies. However, high temperature and humidity levels can cause buttercream frosting to wilt and melt. While buttercream frosting is usually prepared by combining butter and/or shortening, confectioner’s sugar, milk and flavorings, adjusting the ingredients you use as well as the mixing technique will help you create stiff buttercream frosting that is not spongy or runny.
Things You'll Need
Replace butter with double the quantity of high quality shortening. Shortening can withstand high temperatures and has a melting point of 106 degrees Fahrenheit, compared with butter, which begins to melt at around 88 to 98 degrees Fahrenheit.
Add approximately 1 tablespoon of meringue powder or cornstarch to enough frosting to frost a 9-inch x 13-inch cake, or 2 tablespoons to the amount used to frost a two-layer cake. Meringue powder and cornstarch absorb excess moisture from the buttercream, enabling the frosting to hold its shape and remain stiff.
Blend the ingredients manually with a spoon or with an icing spatula until smooth. Alternatively, run an electric mixer at the lowest setting. Combining the buttercream in this way will get rid of the air bubbles and prevent the frosting from getting a spongy texture.
Cover the frosting with a damp muslin cloth until ready to use; or place it in an airtight container in the refrigerator. Re-whip the frosting before using.
Store the buttercream frosting in an airtight container and refrigerate for up to two weeks.
To make stiff frosting easier to spread, add a little milk or corn syrup to it.
References and ResourcesWhat’s Cooking America: Buttercream Icing -- Buttercream Icing 101
Wilton: High Humidity Icing – Recipe 1
Baking 911: Types -- Frosting or Icing, Fillings and Glazes
ResourcesKing Arthur Flour: Quick Buttercream Frosting
Wilton: Buttercream Icing
BBC: How to Make Icing