Toast oats on a baking sheet at 350?F for ~8 minutes until lightly browned.
In a bowl, cream butter with brown and white sugars until fluffy. Beat in egg and vanilla. Separately, mix flour, baking powder, baking soda, salt; gradually add to butter mixture and combine. Fold in the toasted oats, rice cereal, and chopped peanuts.
Drop dough by teaspoonfuls onto ungreased cookie sheets. Bake at 350?F ~8 minutes until edges are golden. Cool on wire racks..