For the crust: Preheat the oven to 350°F. In a medium bowl, blend together the graham cracker crumbs and brown sugar. Drizzle in the butter and mix with a fork until the crumbs are evenly moistened. Press the mixture evenly over the bottom and about halfway up the sides of a 9-inch pie dish. Bake for 6 to 8 minutes. Let cool completely before filling.
For the filling: Preheat the oven to 425°F. Pour the sweetened condensed milk into a shallow baking dish. Cover the pan snugly with aluminum foil. Set the shallow dish in a larger roasting pan and add hot water until it reaches halfway up the side of the baking dish. Bake until a dark caramel color, 1 to 1 1/2 hours. Check occasionally to add more water to the pan as needed. The condensed milk will turn a nice brown caramel color. Carefully remove from the oven and let cool completely.
Whisk out any lumps until smooth and fill the prepared pie crust. Slice the bananas and arrange them on top of the dulce de leche caramel.
Using a stand mixer fitted with the whisk attachment (or in a large mixing bowl using a handheld mixer), whip the cream on medium speed until it starts to thicken. Add the confectioners' sugar and beat until the cream holds nice soft peaks. Refrigerate until ready to serve.
Grate the chocolate on top of the whipped cream just before serving.