1. In a medium bowl, combine flour, baking powder, baking soda, and salt. Set aside.
2. In a large mixing bowl beat butter, peanut butter, sugar, and brown sugar on medium speed until light and fluffy.
3. Add eggs and vanilla and beat well. Stir in flour mixture and cereal.
4. Drop rounded teaspoonfuls onto ungreased baking sheets. Using back of fork, flatten each cookie in crisscross pattern.
5. Bake at 350°F for about 14 minutes or until lightly browned. Remove immediately from baking sheets. Cool on wire racks.