Crust: Mix all crust ingredients together and press in to a 9x!3 pan spray with cooking spray or lined with foil. Refridgerate until you complete the next steps.
Chocolate Ganache Filling: Heat cream in a small pan on the stove until steaming but not boiling, turn off the heat then stir in chocolate chips until smooth. Spread this over prepared crust and then pop back into the refrigerator.
Rice crispies: Melt butter in a large pot on medium low, stir in 9 cups of marshmallows and continue to stir over low medium heat until marshmallows are melted and the mixture is smooth. spray a large bowl with cooking spray, add the rice crispy cereal and the remaining 3 cups of marshmallows. Stir in the melted marshmallow mixture until combined and then press over the crust with the chocolate filling. Chop the chocolate bar and sprinkle on top with some additional mini marshmallows. Drizzle with extra chocolate if you want to be extra fancy. Let cool completely before cutting, usually 2 hours.