In a medium-sized bowl, stir together the graham cracker crumbs and melted butter until evenly combined. Firmly press the mixture into a lightly greased 9-inch pie plate. Bake in preheated oven for 10 minutes. Set aside while you prepare the filling.
For the Chocolate Filling:
Increase oven temperature to 350 degrees (F).
Place both chocolates in a large, heatproof bowl. Using a microwave or double-boiler, melt chocolates, stirring frequently, until completely smooth. Set aside to cool for 10 minutes, then whisk in sweetened condensed milk, egg yolks, vanilla, and salt. The mixture will be quite thick!
Pour chocolate filling into the crust and bake in preheated oven for 18 minutes. Remove pie from oven and cool on a wire rack for 30 minutes before transferring the pie to the fridge to cool completely - about 4 hours.
Once the pie has set, cover the top with marshmallows. Using a kitchen torch, char the marshmallows to desired crispiness (this will happen very fast!). Sprinkle with graham cracker crumbs, slice, and serve!
If you'd like easier to slice pieces, try cutting your marshmallows in half before placing them on top of the pie.If you don't own a kitchen torch, you can heat the marshmallow layer up in the oven, but stay VERY close by, as they toast quickly and can catch on fire. Heating the marshmallows up in the oven will also require you to re-chill the pie for a bit, which is why I recommend using a kitchen torch.This pie will keep, covered tightly in the fridge, for 2 days. For best results, top with marshmallows right before serving, otherwise they get hard and sticky.