Mix graham cracker crumbs, sugar, salt, and melted butter in a medium bowl with a rubber spatula.
Press graham cracker mixture into a 9x9 inch pie plate.
Bake crust for 7-9 minutes, or until firmed up, in the oven.
Hershey's Chocolate Filling
Cut up chocolate bars into small chunks. (this will make it easier to melt)
Combine chocolate, heavy cream, and 1 cup skim milk into a medium saucepan, stirring constantly over medium heat until the mixture comes to a boil. Once the mixture comes to a steady boil, remove from the heat.
In a medium bowl, mix flour, salt, corn starch, and sugar. Set aside.
In a seperate bowl, whisk together egg yolks and remaining 1 cup of skim milk.
Pour egg/milk mixture into the flour/sugar mixture. Gradually add into the chocolate mixture, placing it back over medium heat. Constantly stir with a whisk until the mixture again boils. Let the mixture boil for 1 minute. It should be starting to get more thick.
After mixture has boiled, take off from heat and add in butter and vanilla extract.
Pour chocolate filling into graham cracker crust and cover with plastic wrap. Place pie in refrigerator for at least 3 hours, or overnight.
After pie has completely chilled, arrange marshmallows on top of pie. (I had to use my entire bag). Place pie in the oven under the broiler setting for 3 minutes, or until marshmallows are golden brown. My broiler was set at 575°F.