Preheat oven to 350 degrees
Before you melt the butter for the recipe, use it to grease the 8×8 baking dish. Be sure to grease it heavily. Crush the graham crackers into crumbs, I find the fastest way is to toss them into a food processer.
Pour in the melted butter and mix well.
Dump crumb mixture into the greased pan and pack them onto the bottom of the pan.
In the food processer or using a mixer, beat cream cheese until smooth.
Add the vanilla, egg, sour cream, sugar, and cocoa powder. Mix until fully blended.
Pour cheesecake mixture over graham cracker crust and smooth it as evenly as you can.
Sprinkle the chocolate chips over the cheesecake mixture.
Place in the center of the preheated oven and bake for 20 minutes.
After 20 minutes of baking, add the marshmallows to the top and bake for another 10 minutes.
After 10 minutes if you want your marshmallows to be a little more golden on top, you can turn the oven on hi broil for just a few seconds. Just be sure you really watch it as it will burn fast.