Lightly grease a 9x13" baking dish with non stick cooking spray- then line with parchment paper. Set aside.
Heat the butter in a medium sized pot over medium low heat, just until melted. Add the marshmallows and stir until they're completely melted and the mixture is smooth. Remove the pot from heat.
1/2 cup salted butter, 6-7 cups mini marshmallows
Spray a large mixing bowl with non stick cooking spray. Add the cereal to it, then pour the marshmallow mixture out over top.
8 cups golden grahams cereal
Spray a spatula with non stick cooking spray, and use it to stir the mixture together until all the cereal's evenly coated.
Add half of the chocolate chips to the bowl, folding them in until evenly combined.
1 cup mini chocolate chips
Transfer the mixture to the prepared pan and spread it out in an even layer. Sprinkle the remaining chocolate chips evenly out overtop.
Let the cereal bars rest/set for 2 hours, or until firm.
Slice into squares, serve, and enjoy!