1. In a large saucepan, melt the butter over low heat. Add the marshmallows (reserving a handful for the top) and cook, stirring until fully melted and blended. Remove from heat.
2. Stir in the Golden Grahams cereal until well coated with the marshmallow mixture.
3. Using a buttered spatula, press the cereal mixture firmly into a greased 13×9-inch pan.
4. Melt the chocolate chips in the microwave in 30-second intervals, stirring in between until fully melted.
5. Drizzle the melted chocolate over the bars using a fork.
6. Allow the bars to cool completely before cutting them into squares. Store in an airtight container.