In a food processor or by hand, cream together the margarine, peanut butter, and sugar substitute.

Add the egg, water, and vanilla and continue to mix until well blended.

Combine the flour, baking soda, and baking powder in a sifter; sift dry ingredients into creamed mixture and mix until completely blended.

Refrigerate overnight.

Lightly spray cookie sheets with nonstick cooking spray.

Drop teaspoonfuls onto cookies sheets and press with the tines of a fork to flatten each cookie.

(Use cookie cutters to create decorative cookies if you prefer.

) Bake the cookies at 375 degrees for 12 to 15 minutes, remove from the oven, and let them cool on racks.