Step 1: Preheat your oven to 325°F (160°C).
Step 2: In a mixing bowl, combine the gingersnap cookie crumbs, brown sugar, ground cinnamon, and kosher salt. Add the melted butter and mix until the crumbs are evenly coated. Press this mixture firmly into the bottom of your springform pan to form an even crust.
Step 3: Bake the crust in the preheated oven for about 10 minutes.
Step 4: In a large mixing bowl, beat the cream cheese until smooth and creamy. Add the pumpkin puree and mix. Then, add the eggs, egg yolk, sour cream, sugar, spices, salt, flour, and vanilla extract. Mix until fully combined.
Step 5: Pour the filling over the cooled gingersnap crust in the springform pan. Smooth the top with a spatula. Bake for about 60 to 70 minutes, or until the center is set but slightly jiggly.
Step 6: Once baked, crack the oven door and let the cheesecake cool for about an hour. Then, cool completely at room temperature and refrigerate for at least 4 hours.