Preheat oven to 375 degrees F.
Coat 13 x 9 x 2-inch baking dish with cooking spray.
Cover bottom of pan with single-layer of graham crackers (you may need to break them to cover completely).
Spread marshmallows evenly on top of crackers.
Roughly chop peanut butter chips and sprinkle them over the marshmallows.
Bake for 8 minutes or until marshmallows are "puffy." Cool completely.
In microwave-safe bowl (or on the stove), mix chocolate chips, corn syrup and butter. Microwave on high for about a minute and a half or until chocolate is melted. Stir every 30 seconds.
Once chocolate is melted, stir in peanut butter until smooth.
Add Rice Krispies and stir until coated. Spread over the marshmallows.
Cover and refrigerate for an hour or until firm. Store in an airtight container in refrigerator.