To make this S'mores Pie, preheat your oven to 350 degrees and start with the graham cracker crumb crust. Lightly butter a 9 inch pie pan. In a large mixing bowl, combine graham cracker crumbs, melted butter, sugar and salt. Stir well until mixed and then press crumbs evenly into the bottom and up the sides of your pie pan and set aside.
Next, add your heavy cream to a small saucepan and bring to a low boil. Add the chocolate chips, brewed coffee and a pinch of salt to a bowl and then pour the heated heavy cream over your chips. Let sit for 1 minute before whisking to combine and melt chocolate. Once your chocolate is melted, whisk in the egg and then pour chocolate filling into your prepared pie pan.
The pie filling will only come up about half way up the pie crust. To make sure your graham cracker crumb crust does not melt, cover the edge with tin foil before baking. Bake for 30-35 or until the chocolate pie is soft set and only jiggles slightly when shaken. Once baked, remove from oven and let cool.
When ready to serve, place the marshmallows on your pie and heat your oven broiler. Set your oven on Broil, prop the oven door open a bit, move your oven rack to the second highest level and move your pie right under the broiler for 20-30 seconds or until your marshmallows are dark and toasty. Remove from the oven and using a kitchen towel, lightly press down on your marshmallows to push them together, making a solid marshmallow layer. Serve immediately.