Prepare brownie mix according to package directions, using a greased 13-by-9-by-2-inch baking pan. Cool on wire rack. In a large saucepan, combine the chocolate chips and peanut butter. Cook over low heat for 4–5 minutes or until blended, stirring occasionally. Stir in cereal; set aside.
Spread frosting over brownies. Sprinkle with peanuts. Spread with peanut butter mixture. Chill for 30 minutes or until set before cutting. Store in refrigerator.