Use a container of whipped frosting in a bowl and give it an extra whip with your mixer. (I do this anyways cuz it fluffs up the frosting and makes it go further.)
Then take the cupcake in your hand, turn it upside down. Put it in the frosting bowl, turn and pull it out. It works great and is much neater than trying to use a knife. Even my kids can do it.
Head back to Shannon’s for more WFMW ideas.