HT to Barb Kavouras for this puppy, only slightly modified:
1 cup peanut butter
1 cup Splenda
small splash vanilla
Mix together. Form into round balls and put on greased cookie sheet. Smoosh with bottom of a glass, imprint top with criss-crossed fork marks, and bake in preheated 350 oven for 8 minutes. Hard to believe such a tasty cookie can be so simple!!! Go on, try it out. Dare you.