If you being with slightly warmer butter in creating the packet, you can shape it as you like, and then chill it until it's firm. (glutenfreeonashoestring.com)
As I baked the sugar cookie bar base and the smell of warm butter and sugar filled the air, kids started filing through the kitchen wondering aloud what I was making. (foodiewithfamily.com)
It is easiest to do this by warming the butter to room temperature and then working it in a few chunks at a time. (sarahcupcake.com)