Preheat the oven to 325F degrees and lightly grease a 9-inch pie plate with non-stick cooking spray.
In a medium bowl, stir together the graham crumbs, sugar and melted butter until evenly combined.
Press the mixture into the bottom and up the sides of the pie plate (I use the bottom of a measuring). Place in the fridge as you make the filling.
Chop the chocolate into very small pieces (if not using chocolate chips) and place in a large glass bowl.
Heat the cream until almost boiling - either in the microwave or in a saucepan while gently stirring.
Pour the hot cream over top of the chocolate and let sit for 3-5 minutes. Whisk the mixture til smooth.
Whisk in the eggs.
Pour the chocolate mixture into the pie shell.
Bake in the preheated oven for 25-30 minutes, or until the filling no longer looks liquidy when you give the pie plate a gently nudge.
Remove from the oven. Cool the pie completely, then cover and place in the fridge for 4 hours (or overnight).
When ready to serve, turn the oven to broil and position an oven rack in the lower third of your oven.
Sprinkle the top of the pie with marshmallows.
Place the pie in the oven for a few minutes. Watch carefully, and remove the pie as soon as the marshmallows start to get golden brown on top. They can burn quickly, so do not walk away from the oven.
Slice into pieces and serve.