Buttercream Frosting with cream cheese/Must be refrigerated within 2 hours of frosting. Royal Icing made with powdered sugar, meringue powder, and water/Must be refrigerated within 2 hours of frosting. French Buttercream Frosting adds egg yolks to the recipe/Must be refrigerated within 2 hours of frosting.

Can you store icing at room temperature?

If you're planning to serve your frosted cake or treat within 3 days of making it, you can store it, covered, at room temperature. Otherwise, decorated treats are best kept in the fridge.

Can you leave icing unrefrigerated?

Due to the large amount of confectioners' sugar and a small amount of milk in American buttercream, it is safe to leave it out for up to three days. After three days, any frosted items should be stored in the fridge to maintain freshness and texture.