Preheat oven to 350 degrees F. Lightly grease a 9-inch pie plate and set aside.
Crust: In a medium bowl, combine graham cracker crumbs, ground hazelnuts, cocoa powder, sugar, and melted butter. Press mixture into the bottom and sides of prepared pie plate. Reverse about 2 tablespoons of crust mixture to use later to top finished pie. Set aside.
Filling: In a large bowl, beat cream cheese until smooth. Add sugar until combined. Scrape down bowl as needed to ensure thorough mixing. Add eggs one at a time until incorporated. Add pumpkin puree, cinnamon, and salt. Continue to mix on low speed until smooth and thoroughly combined.
Pour mixture into prepared crust. Bake for 50 minutes until the center of the pie is set and no longer jiggles. Remove from oven and allow to cool on rack for an hour until filling has cooled to about room temperature.
Topping: Place chocolate and cream in a small bowl over a bain-marie. Gently melt chocolate over low heat until smooth. Remove from heat and allow to cool for about 10 minutes. Pour melted chocolate over cooled pie. Spread into an even layer. Sprinkle chopped hazelnuts and reserved crust mixture on top. Chill uncovered in the fridge for one hour until chocolate has set. Place pie in an airtight container (or cover with plastic wrap) and allow to chill for another 2 hours (or overnight) until ready to serve.