Lightly grease a 9x13 inch pan with butter or non-stick cooking spray.

In a large saucepan over low heat melt the butter, mini marshmallows, and peanut butter stirring until fully combined.

Once melted, remove from heat and stir in the Rice Krispies cereal.

Press the mixture into the prepared pan, spraying your hands with cooking spray makes this step easier.

Using a microwave-safe bowl, microwave the chocolate for 45-second intervals, stirring well after each interval.

Once almost melted and fully smooth, stir in the corn syrup.

Pour the chocolate on top of the bars, spread evenly and let harden at room temperature for about 2 hours.

Cut into squares and store in an airtight container at room temperature.