Stable Buttercream

Preventing buttercream from melting requires both proper technique and strategic stabilization. The butter must be at perfect room temperature - soft enough to cream but not so warm it lacks structure. 

Extended beating (6-8 minutes) incorporates maximum air, creating stability through proper emulsification. 

Adding cornstarch acts as a stabilizer, absorbing excess moisture and providing structure that resists heat. Sift cornstarch with some of the powdered sugar to prevent lumps. The finished buttercream should hold soft peaks and maintain structure at room temperature. 

Store in cool conditions and avoid applying to warm cake. This technique is especially crucial for citrus buttercreams where acid can affect stability.