If crunch mixture starts to set up, place in microwave and microcook 15 seconds or until slightly sticky.
Position oven rack about 8 inches below broiler. Preheat broiler. Line a baking sheet with foil; set aside. Cut 12 large marshmallows in half; set aside. Break each of 12 whole graham cracker planks in quarters. Spread half the quarters with warm chocolate, place on prepared sheet. Top with marshmmallow half. Broil about 2 minutes, until marshmallows are soft and melted, watching closely to prevent burning. Top remaining quarters with chocolate-cereal mixture. While warm, sandwich layers together.