Preheat oven to 325°F (163°C). Lightly grease a 9-inch springform pan.
In a medium bowl, mix crushed cookies and melted butter. Press mixture into the bottom of the pan and bake for 10 minutes. Let cool.
In a large bowl, beat cream cheese and sugar until smooth. Add pumpkin, eggs, vanilla, sour cream, pumpkin spice, and salt. Mix until combined.
Pour most of the pumpkin mixture into the crust, reserving about 1 cup.
Stir melted chocolate into the reserved cup of pumpkin filling.
Drop spoonfuls of the chocolate filling over the top of the pumpkin layer. Use a knife or skewer to gently swirl for a marbled effect.
Bake for 55–60 minutes, or until center is just set.
Turn off oven, crack the door, and let cheesecake cool for 1 hour. Then refrigerate for at least 4 hours or overnight.
Before serving, garnish with whipped cream, chocolate shavings, or nuts if desired.