Preheat the oven to 325°F (165°C).

To make the crust, place the graham crackers in a food processor and pulse until you start seeing fine crumbs. Add the cacao powder and salt and pulse to combine. Pour the crumbs into a mixing bowl, and add the vegan butter. Mix to combine. Transfer the crumbs to a 9-inch (23-cm) pie pan, pressing on all sides until the pan is covered with the graham crumbs. Bake for 5 minutes. Let it cool completely before adding the filling.

To make the filling, add the coconut milk, chocolate and hazelnut spread, vanilla extract and salt to a saucepan and bring it to a boil over medium heat, stirring until well combined. Place the chocolate in a heat-safe bowl. Pour the boiling mixture over the chocolate and let it sit for 2 minutes. Mix with a spatula until everything is well combined.

Pour the filling into the crust. Transfer the pan to the refrigerator and let it chill for at least 1 hour to set. Top the pie with chopped hazelnuts or other nuts, if using.