In 2-quart saucepan, heat corn syrup, butter, peanut butter chips and vanilla over medium heat 2 to 3 minutes, stirring constantly, until chips are melted. Remove from heat; stir in cereal and peanuts. Spread evenly over marshmallows. Refrigerate about 1 1/2 hours or until firm. Cut into 4 rows by 4 rows. Store in refrigerator.