Could this be made with all butter or is the shortening necessary for the proper texture?

Hi Michelle, according to Jessie, the shortening, which has a higher melting point than butter, is to help the cookies keep their shape in the oven and prevent spreading (which, as HalfPint said, would make them harder and crispier). I used a non-hydrogenated brand called Nutiva and it worked great. I bet they'd still be pretty tasty with all butter though, if you want to work with what you have now.

The shortening is there for texture. All butter will result in a harder, more crispy cookie.