Preheat your oven to 350°F (175°C). In a medium bowl, combine graham cracker crumbs, sugar, melted butter, and salt. Mix until the crumbs are evenly moistened.
Press the mixture firmly into the bottom and up the sides of a 9-inch pie plate. Use the bottom of a measuring cup to create an even, compact layer.
Bake the crust for 8 minutes until lightly golden. Remove from oven and let cool while preparing the filling.
In a large mixing bowl, whisk together the pumpkin puree and brown sugar until well combined. Add the eggs one at a time, whisking well after each addition.
Stir in the vanilla extract, pumpkin pie spice, cinnamon, and salt. Gradually add the evaporated milk while whisking continuously to prevent lumps.
Pour the pumpkin filling into the pre-baked graham cracker crust. Smooth the top with a spatula.
Bake at 350°F for 45-50 minutes, or until the center is almost set but still slightly jiggly. A knife inserted 1 inch from the edge should come out clean.
Allow the pie to cool completely at room temperature, about 2 hours.
Once the pie is completely cooled, prepare the marshmallow topping. In a microwave-safe bowl, combine mini marshmallows and butter.
Microwave in 20-second intervals, stirring between each, until marshmallows are melted and smooth, about 1-1.5 minutes total. Stir in vanilla extract immediately.
Pour the marshmallow mixture over the cooled pumpkin pie, using a spatula to spread it to the edges in decorative swirls.
For an extra-special presentation, use a kitchen torch to lightly toast the marshmallow topping until golden brown. Alternatively, place under a broiler for 1-2 minutes, watching very carefully to prevent burning.
Let the pie set for 10 minutes before slicing and serving.