Make the Crust: In a medium bowl, stir together the graham cracker crumbs, brown sugar, and salt, ensuring no lumps of brown sugar remain. Drizzle the melted butter over the graham cracker mixture and toss to combine with a fork, ensuring that the mixture is evenly moistened. Press the crust mixture evenly into the bottom and up the sides of a 9-inch pie plate, and pack tightly using the back of a measuring cup. Place in the freezer for at least 15 minutes.
Assemble the Filling: Arrange the sliced bananas on the crust, then spread the dulce de leche over top of the bananas.
Make the Coffee Whipped Cream: In a large bowl, whisk the espresso powder into the heavy cream until dissolved. Add the sugar and vanilla and, using an electric mixer, whip on medium speed until frothy and beginning to thicken (2 to 3 minutes). Increase the speed to medium-high and beat for another 30 seconds to 1 minute, or until the cream looks billowy and there are distinct trails left by the whisk in the whipped cream.
Spread the whipped cream over the filling and garnish with chopped hazelnuts (or peanuts) and shaved chocolate, if desired, and serve. Cover leftovers with plastic wrap and refrigerate for up to 3 days.
Crust - You can substitute other types of crackers/biscuits or use other alternatives like Oreo, chocolate graham cracker, etc.
Dulce de Leche - I use canned dulce de leche for this pie, but if you wish to make your own, you need to boil an unopened can of sweetened condensed milk. For detailed instructions, see this post from Serious Eats.
Coffee Whipped Cream - You can substitute plain homemade whipped cream; see the post above for other topping options.
Make-Ahead - You can make prepare the graham cracker crust, cover and freeze the pie plate for up to 3 months. The entire pie can be assembled 1 day in advance. I do not recommend freezing this pie.