Lightly coat a 9-inch springform pan with nonstick spray and set aside.
Add the cookies to a ziplock bag, and crush them using a rolling pin.
Add the cookie crumbs and melted butter to a large bowl and stir until well combined.
Add the mixture to the prepared springform pan and using a measuring cup, press it to line the sides about 1 inch up of the pan edges.
Refrigerate for at least 20 minutes.
Add 2/3 cup of cold water to a small bowl, sprinkle the gelatin on top. Let it bloom for 1-2 minutes. Whisk to combine, microwave for 30 seconds and whisk until fully combine and a gelatin mixture is formed. Set aside.
Add the 20 ounces of chopped chocolate to a medium bowl, microwave in 30 seconds increments and stir until the chocolate is fully melted. The mixture should be smooth and shiny. Set aside to cool.
In a large bowl, using an electric hand mixer or stand mixer, beat cream cheese, add Nutella and melted chocolate and beat until combined. Stop a few times to scrape the sides and bottom of the bowl.
Add cold whipping cream to a medium bowl, add the gelatin mixture to it and whisk manually to combine.
Add the cream and gelatin mixture to the cream cheese mixture and using a mixer beat it until fully combined.
Spread the cheesecake filling evenly onto the prepared pan.
Set the cheesecake in the refrigerator to chill and firm, 5-6 hours or better, overnight.
Whipped Cream (optional):
Add the heavy cream, sugar and vanilla, to a large bowl and whisk until stiff peaks form.
Add to a piping bag fitted with the star tip and pipe around the cake edges or just serve on the side of individual slices.
Garnish with mini Oreos.
Cut the Cheesecake:
Run a butter knife around the edges of the cheesecake. Remove the pan ring.
Cut into slices, washing the knife after each slice and serve.