Start by ensuring your butter is very soft before you begin mixing.
Combine the icing sugar with the softened butter, maintaining a ratio of at least 2:1 icing sugar to block butter.
If you're in a hot environment, consider using a thick layer of white chocolate ganache as a crumb coat to help stabilize the buttercream.
This buttercream will remain stable at room temperature up to 30 degrees Celsius and will start to soften between 32-35 degrees.
