Preheat an oven to 325 degrees F.
In mixing bowl, mix butter, erythritol, stevia, egg, and vanilla until well blended.
In a separate bowl, add all the dry ingredients and mix until well combined.
Add the dry mixture to the wet mixture and mix again until well blended.
If desired, chocolate chips or nuts can be mixed in at this time.
Shape the mixture into a large ball of dough. Place dough ball on a silicon baking pad or a well greased cookie sheet. Shape dough into a low, flat log.
Bake the dough for about 20 minutes, or until lightly browned and cake-like.
Remove from oven and reduce the temperature to 275 degrees F.
Cool the log for about 10 minutes and then slice into thin strips about 1/2 inch wide.
Place the slices on their side on the cookie sheet, and then bake for about 20-30 minutes, or until they are fully crisped.
Recipe makes about 15 cookies.