Combine margarine, peanut butter, sugars, egg and vanilla.
In a separate bowl sift together dry ingredients and add to wet mixture.
Form into small balls, roll in remaining sugar and flatten with a fork... creating a criss-cross design.
Bake 10-12 minutes until practically perfect.
Note: You can substitute butter for the margarine, but I actually prefer the reduced-fat margarine in this recipe. Also, be careful not to over-bake. These cookies are best when they're a little under-done.