Butter cream frosting is a sweet frosting; its base is sugar and butter. Add some milk and vegetable shortening, and the recipe creates a versatile cake spread. The biggest problem when making butter cream frosting is the issue of bubbles. The butter includes natural trapped air and the sugar pulls air into itself while it is being worked. Pull the air bubbles out of the frosting for a smooth, bubble-free surface.
Mix the butter cream frosting slowly when the sugar is added to avoid getting air bubbles during the preparation. Use a mixer and do not whip the sugar into the mix; rather, use a very slow mixing motion.
Stir the butter cream frosting with a wooden spoon, spatula or on a low mixing speed to remove any air bubbles which were missed during Step 1. Stir slowly and for a long time. Some recipes ask for the frosting to be mixed for 25 minutes to ensure the bubbles are gone.
Store the butter cream frosting in a zip-top bag overnight to allow the mixture to rest. In the morning, cut a hole in a corner of the bag and push the butter cream through the hole into a bowl. Any remaining air bubbles will be pushed out of the frosting while it is being moved through the hole.
Stir the frosting with a wooden spoon if there are remaining air bubbles; then push it through the zip-top bag again. All the air bubbles will be removed after these processes.