Line a large baking sheet with parchment paper.

Place milk chocolate chips in a microwave-safe bowl. Microwave in 30-second intervals, stirring in between, until smooth and fully melted.

Pour the melted chocolate onto the prepared baking sheet and spread evenly with a spatula to about 1/4 inch thickness.

Drop spoonfuls of marshmallow fluff onto the wet chocolate. Use a knife or toothpick to swirl the fluff into the chocolate for a marbled look.

Immediately press broken graham cracker pieces and crumbs onto the surface of the bark.

Place the tray in the refrigerator for 45-60 minutes until the chocolate is completely set and hard.

Remove from fridge and use your hands to snap the bark into uneven pieces. Serve immediately or store in an airtight container.