Grease a 9×13 inch baking pan with butter or margarine. Set aside.
In a large non-stick pot over medium heat, melt butter or margarine. Add in marshmallows and 1 cup of chocolate chips. Stir together with butter until everything is melted together and creamy.
Fold in graham cereal until marshmallows and cereal are evenly coated. Mix in 1/4 cup of chocolate chips.
Spread the cereal into the baking pan, and using clean, greased fingers, press into a single layer.
Sprinkle the remaining 1/4 cup of chocolate chips and 1/4 c mini marshmallows on top of the treats and lightly press again to make sure they stick.
Let cool at room temperature, then place into the refrigerator for 10 minutes to chill. Cut into 12 squares, and enjoy!