HEAT oven to 350°F.
COMBINE first 5 ingredients. Beat peanut butter, butter and sugar in large bowl with mixer until light and fluffy. Add egg and vanilla; mix well. Gradually beat in flour mixture until well blended.
DROP heaping tablespoonfuls of dough, 2 inches apart, onto baking sheets.
BAKE 10 to 12 min. or until lightly browned. Cool on baking sheet 1 min. Remove to wire racks; cool completely.