In 4-quart saucepan, heat corn syrup, butter, vanilla and peanut butter chips over medium heat, stirring constantly, just until melted and smooth. Remove from heat. Stir in cereal and peanuts. Immediately spoon warm topping over marshmallows; spread to cover. Refrigerate until firm, about 45 minutes. For bars, cut into 6 rows by 6 rows.