1. Preheat oven to 350°.
2. Beat peanut butter and margarine with a mixer at medium speed until blended.
3. Lightly spoon flour into dry measuring cups; level with a knife. Combine flour and sweetener in a medium bowl. Add flour mixture to peanut butter mixture, beating well. Add egg and vanilla; beat well.
4. Shape dough into 24 (1-inch) balls. Place balls, 2 inches apart, on ungreased baking sheets; flatten cookies in a crisscross pattern with a fork. Bake at 350° for 12 minutes. Cool completely on baking sheets.
carbo rating: 4