In a large bowl, add Golden Grahams, and set aside.
In a large pan, melt the butter over low heat. Once melted, add 16 ounces of mini marshmallows to the pan and stir until completely melted and smooth.
Turn off the heat and add 1/2 cup of mini semi-sweet chocolate chips to the pan. Stir gently until the chocolate is melted and incorporated.
Pour the marshmallow mixture over the cereal and mix to combine. Be care complete not to crush the cereal.
Add the remaining mini marshmallows to the mixture and stir gently. The goal is to incorporate them without melting them entirely, as this will create delightful pockets of gooey marshmallows in the final result.
Spray a sheet pan with cooking spray to prevent sticking. Transfer the mixture to the prepared pan and spread it evenly using a spatula.
To add an extra touch of texture and visual appeal, sprinkle 1/4 cup of Golden Graham's cereal and 1/4 cup of mini semi-sweet chocolate chips on top of the mixture in the baking dish.
Allow the Indoor S'mores to set up for a few minutes. This will allow them to firm up slightly, making them easier to cut into individual portions.
Once the s'mores have set, it's time to enjoy this delectable treat! Cut them into squares or rectangles, and serve them while they're still slightly warm for that irresistible melt-in-your-mouth experience.