For the Crust: Spray a 6-inch (3” deep) spring form pan with cooking spray. In a medium bowl, stir together the dry crust ingredients until completely incorporated. Mix in the melted butter then press evenly into the bottom and one inch up the side of the prepared pan.
For Filling: In a stand mixer fitted with a paddle, beat together the cream cheese and sugar until fluffy, about 5 minutes. Add the salt and vanilla extract, and continue beating. Beat in one egg at a time, making sure to incorporate fully between each addition.
Once the eggs are combined, beat in the sour cream and then heavy cream. Mix just until combined. Transfer 1/2 cup of batter to a medium bowl and set aside.
Pour large portion of batter over the prepared crust.
Mix the pumpkin purée, cinnamon, ginger and nutmeg into the bowl with the reserved batter. Dollop over the cheesecake in 4 places. Using a skewer or butter knife, create a swirl by inserting skewer into a dollop and twirling around the pan without scraping the bottom. Repeat with the remaining dollops of flavored batter.
Make a foil rack in the bottom of a round or oval 6- or 7-quart slow cooker then fill with half an inch of water. Place the cheesecake inside. Place 4 layers of paper towels on the top of slow cooker then place lid on. Set on high and cook for 2 hours. Without opening the lid, turn the heat off and allow the cheesecake to cool for 1 hour.
Remove cheesecake from slow cooker and cool to room temperature then refrigerate for at least 2 hours.
Whip the heavy cream into soft peaks with the cocoa and powdered sugar.
Remove cheesecake from pan, cut slices with warm knife and serve each slice with a dollop of chocolate whipped cream.