A Bit of Frost-y Advice...

If you're making something that calls for a rich, creamy, fluffy looking frosting (like a cupcake), use soft (un-melted) butter when you make it.

However, if you're frosting something you later intend to layer or stack, like these...
... make a simple icing of powdered sugar, milk, and a splash of vanilla. It will "set up" just enough that the cookies won't stick or smear.
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This post is linked to:

Cupcake Tuesday at Hoosier Homemade.
Works For Me Wednesday at We Are THAT Family.