Andy M.
Certified Pretend Chef
I'm prejudiced, obviously, but I really don't think butter or butter-flavored shortening would improve these cookies one bit. They have a distinct peanut flavor with what seems to me to be a hint of honey, and they're crisp but light in texture.
My suggestion wasn't for your mom's recipe, Scotch. It was in response to the OP. I have copied your mom;s recipe for later use.