Mix brown sugar, margarine, peanut butter, egg and vanilla. Stir in flour, baking soda and salt. Cover and refrigerate at least 2 hours. Heat oven to 180ºC . Shape dough into 3 cm balls; roll in cereal. Place about 5 cm apart on ungreased cookie sheet. Bake until almost no indentation remains when touched, dozen to 13 minutes. Makes about 4.5 dozen. ----