Preheat oven to 350'F. Lightly grease cookie sheet. In large bowl, cream peanut butter, margarine and sugar. Add egg. Stir in flour and baking powder; add salt, if desired. Stir in cereal; mix well. For each cookie, roll 1 level tablespoon dough into ball. Place on prepared cookie sheet. With fork dipped in sugar, flatten slightly in criss-cross pattern. Bake 8-10 minutes or until bottoms are lightly browned. Let stand 1 minute before removing from cookie sheet. Cool on wire rack.
