Measure the Golden Grahams cereal into a large mixing bowl and set aside.
In a microwave-safe bowl, combine chocolate chips and peanut butter. Microwave in 30-second intervals, stirring after each, until completely melted and smooth (about 1.5 minutes total).
Pour the melted chocolate mixture over the cereal and gently fold with a spatula until every piece is evenly coated.
Transfer the coated cereal to a large zip-top bag, add the powdered sugar, seal tightly, and shake vigorously for 1-2 minutes until all pieces are thoroughly covered in white powder.
Spread the mixture onto a large sheet of parchment paper and let cool for 10 minutes until the chocolate sets completely.
Once cooled, gently fold in the mini marshmallows, then transfer to an airtight container or serving bowl.
