For the graham cracker crust:
1 package graham crackers (9 crackers), crumbled
1/4 cup sugar
5 Tbl unsalted butter, melted
For the chocolate filling:
7 oz bittersweet chocolate, finely chopped
1 cup heavy cream
1 large egg
pinch of salt
For the marshmallow topping:
1/4 cup cool water
1 1/2 tsp unflavored gelatin
1 cup granulated sugar
1/2 cup corn syrup
2 Tbl water
pinch of salt
1 1/2 tsp vanilla
For the graham cracker crust: Preheat the oven to 325ᵒF and arrange a rack in the middle of the oven. Place the crumbled graham crackers in the bowl of a food processor, and pulse until finely ground. (If you don’t have a food processor, place the crackers in a large zip-lock bag, then crush the crackers with a rolling pin.) Add the sugar and melted butter and pulse or stir until well combined. Evenly press the mixture into the bottoms and sides of a 9-inch glass pie plate, forming a neat border around the edge. Bake until the crust is set and golden, about 15 minutes. Set aside on a wire rack. (Leave the oven on.)
For the chocolate filling: Place the chocolate in a medium-sized mixing bowl. Bring the cream to a boil, then pour the hot cream over the chocolate. Let the chocolate and cream stand for about 2 minutes, and then whisk until the chocolate is melted and the mixture is well combined and smooth. Add the egg and a pinch of salt and whisk gently until jut combined. Pour the chocolate mixture into the graham cracker crust. Bake until the filling is softly set, about 25-30 minutes. Cool pie to room temperature on a wire rack, about 1 hour.
For the marshmallow topping: (Precede with these steps, only once the chocolate pie is cooled to room temperature.) Add the 1/4 water to the bowl of an electric stand mixer, then evenly sprinkle the gelatin over the surface of the water. Allow it to rest 10 minutes. Combine the sugar, corn syrup and 2 Tbl water in a small sauce pan, and bring to a boil over medium-high heat. Boil until the temperature reaches 250ᵒF (the hard-ball stage).
Using the whisk attachment, and running the stand mixer at low speed, drizzle the hot sugar syrup into the gelatin mixture (avoid the whisk). Once all the syrup is added, add the pinch of salt and increase the speed to high. Whisk until the mixture is light and fluffy, about 5-6 minutes. Add the vanilla, and mix to combine.
Pour the marshmallow mixture over the cooled chocolate filling, smoothing the top with a rubber spatula, and making sure to keep the marshmallow topping within the crust border.
Chill uncovered for 1 hour, then cover loosely with plastic wrap and continue to chill for 4 more hours, or up to one day.
When ready to serve, protect the edges of the pie with the pie shield or foil and place the pie about 4-inches beneath the oven broil. Broil until the marshmallow topping is evenly golden brown, about 3-4 minutes, rotating the pie frequently while it broils. Alternatively, brown the top of the pie with a blow torch. Slice the pie with a thin, sharp knife, wiping the knife clean with a damp towel between each slice.