Preheat oven to 360º F. Line a 8” x 8” pan with parchment paper, leaving overhang on opposite sides to lift bars out.
Layout graham crackers in bottom of pan. Don’t overlap, but cover completely. You will have to cut some of the crackers to fit.
Sprinkle marshmallows evenly over the graham crackers. Bake for 7 minutes, or until marshmallows are very puffy. Transfer the pan to a rack and allow to cool completely.
Add chocolate chips, corn syrup and butter to a large microwave-safe bowl. Microwave in 30 second bursts on 50% power, stirring between each, until the mixture is melted and smooth. Stir in peanut butter. Fold in rice crisps until combined.
Sprinkle the extras evenly over the marshmallows. Press the rice crisps mixture into an even layer over top. Cover and refrigerate for 1 hour or until firm. Cut into squares when ready. Store in air-tight container in refrigerator.
I like them at room temperature, so remove to counter top 1/2 hour before serving.