In a bowl, whisk the egg. Add in the stevia and vanilla, and whisk again
Stir in the peanut butter, stirring well. That's it! That's the dough! You can add anything else at this point (chocolate chips would be DIVINE) if you'd like
Measure out 1 tablespoon of cookie dough, and roll into a ball. Place onto a greased cookie sheet, and create a crosshatch pattern with the back of a fork. Repeat for the entire batch of dough
Bake for 12-13 minutes. They will be slightly underdone when coming out of the oven, but will harden up.