In a food processor, pulse the graham crackers until crumbs form.
Add the sugar and melted butter, and pulse until combined.
Press the crust mixture into the bottom and partly up the sides of a springform pan.
Layer the Hershey's chocolate bar pieces on the bottom of the crust.
Add the vanilla ice cream on top of the chocolate and spread out evenly.
Sprinkle 2 cups of the marshmallows on top of the vanilla ice cream.
Top the marshmallows with chocolate ice cream and spread out evenly.
If using a creme brulee torch (or something like it), top the chocolate ice cream with the remaining marshmallows and torch until brown.
If using a broiler, place marshmallows on a baking sheet lined with greased aluminum foil. Broil for 30-90 seconds, watching closely, until golden brown.
Top chocolate ice cream with broiled marshmallows.
Sprinkle marshmallows with graham cracker crumbs and Hershey's chocolate.
Cover and place in the freezer for at least 2 hours.
Remove from the springform pan, cut into slices, and enjoy!