Preheat oven to 350 degrees F.
In a large bowl, beat SPLENDA® Brown Sugar Blend, SPLENDA® Sugar Blend, margarine, and peanut butter until smooth. Add egg whites and vanilla. Beat until light.
In another large bowl, combine flour, baking soda, and salt. Stir flour mixture into peanut butter mixture. Shape into 1-inch balls and place on lightly greased baking sheets.
Using a fork that has been dipped in water, flatten cookies in cross-hatch pattern.
Bake 10 minutes or just until cookies are set and look slightly underdone. Cool on sheets 2 minutes. Remove to wire racks; cool completely.