Preheat the oven to 350 degrees F.
Mix the peanut butter and Splenda until creamy.Beat the egg and add the baking soda.
Add the egg mixture to the peanut butter mixture. Mix well.
Drop by teaspoonfuls on an ungreased baking sheet, 2? apart.
Dip a fork in the sugar substitute and make a criss-cross pattern on the cookies.
Bake for about 10 minutes (until slightly browned, but still soft to the touch).
Let cool on cookie sheet for about 2 minutes.Transfer to a wire rack until cooled.