1. For crust, in a medium bowl stir together the crust ingredients. Press crumb mixture into bottom and 1 inch up sides of buttered 10-1/2-inch springform pan. Bake in a 350 degree F oven for 8 to 10 minutes just until color starts to deepen. Remove from oven and set aside.
2. For filling, in a large mixing bowl combine cream cheese and butter; beat with an electric mixer on medium speed until smooth. Beat in sugar, scraping sides of bowl occasionally. Add mashed sweet potatoes, nutmeg, and cinnamon; beat to combine. Add bourbon and vanilla. Mix until thoroughly combined and smooth. Add eggs, one a t a time, mixing just until combined after each addition.
3. Pour filling into prepared crust. Bake in a 350 degree F oven for 20 minutes. Reduce oven temperature to 300 degree F; continue baking for 35 minutes more. Reduce oven temperature again to 250 degrees F, continue baking for 20 to 30 minutes more or until cheesecake is set around the edge and barely jiggles at the center. Remove cheesecake from the oven. Increase oven temperature to 350 degree F.
4. Meanwhile, for topping, whisk together the sour cream, sugar, and bourbon. Carefully spread topping evenly over cheesecake. Bake for 5 minutes more to just set the topping. Remove from oven and let cool for 5 minutes. Run a thin-bladed knife around the edge of the pan and let cool completely. Cover and chill for several hours. Remove cheesecake from pan. If desired, sprinkle with additional gingersnap crumbs. Makes 16 servings.
5. Make-Ahead Tip: Prepare cheesecake as directed and refrigerate, tightly wrapped in plastic wrap, for up to 48 hours.