In a large saucepan melt butter over medium heat. Add the marshmallows and stir constantly until marshmallows are almost melted. Remove from heat.
Quickly add the Golden Grahams cereal. Stir until the cereal is fully coated in marshmallow.
Spray a 13 x 9-inch baking dish with non-stick cooking spray. Pour the cereal mixture into the baking dish and lightly press the mixture down evenly.
Sprinkle 1/3 cup of the chocolate chips on top of the treats. Melt the remaining chocolate chips for 30 seconds in the microwave. Drizzle evenly all over the top. Cool for 20 minutes. Once cooled cut into bars to enjoy!