Preheat oven to 350 degrees F. Line a muffin tin with lines.
Combine the melted butter and graham crumbs together, mixing well until combined. Spoon about 1/2 tablespoon into each cupcake liner, pressing with the back of a spoon to form a crust.
To make the cupcakes, whisk egg and sugar together in a large bowl until combined and no lumps remain. Add in vanilla extract and butter, then whisk in pumpkin puree. Add in flour, baking soda, powder, salt and pumpkin spice, then add in milk and stir until combined and smooth. Drop about 1/4 cup of batter on top of each graham cracker crust, filling the liners 3/4 of the way full. Bake for 16-18 minutes, or until cupcakes are set and spring back at the touch. Let cool completely.
While cupcakes are baking, heat the heavy cream until warm. Pour over the chopped milk chocolate in a large bowl, then use a spoon or whisk to stir until melted and combined. Let sit until cupcakes are cool, then fill a pastry bag with the chocolate and insert the top straight down into the cupcake, squeezing the ganache inside. You can also use a ziplock bag as your pastry bag or a small spoon – cutting off a small hole in the top of the cupcake and spoon the mixture down in.
To make the frosting, combine the egg whites, sugar and cream of tartar in a heat-proof bowl, preferably the bowl of your electric stand mixer. Place over top of a double-boiler that contains simmering water, and whisk constantly for 3-4 minutes until the sugar has dissolved and the egg whites are slightly warm. Immediately remove the bowl and place it on your stand mixer with the whisk attachment, beating slow at first and gradually increasing the speed to high. Beat for 6-7 minutes until glossy and thick, then beat in vanilla extract for another minute until combined. Frost cupcakes! You can torch the frosting if you’d like, as well as cover the top in additional graham crumbs. I stored these at room temp in a large tupperware container with the layer of plastic wrap over top.