1preheat the oven to 325°. Coat a 9 inch springform pan with nonstick spray.
Mix ginger snap crumbs and graham cracker crumbs for the crust in a bowl. Add pecans. Stir in butter, the 2 tablespoon sugar, and salt until mixture is Sandy. Press crumbs into bottom and 1 inch up sides of the prepared pan. Bake crust until slightly Golden, about 10 minutes. Remove pan from the oven. Cool slightly.
2Using a hand mixer on medium speed, beat cream cheese and the 1 cup sugar in a bowl until mixture is fluffy. Add pumpkin, eggs, lemon juice, vanilla, cinnamon, ginger, nutmeg. Beat mixture until smooth, scraping sides of the bowl. Pour filling into crust. Place springform pan on a baking sheet.
3Bake cheesecake until sides are set but center still is jiggly, about 50 minutes. Remove cheesecake from oven. Leave the oven on.
4Whisk together sour cream and powdered sugar in a bowl. Spread topping over the cheesecake. Return the cheesecake to the oven and bake until set, 15 minutes more. Turn off the oven and cracked open the door. Leave the cheesecake in the oven for 20 minutes more.
Remove cheesecake from the top. Allow cheesecake to cool in the pan on a rack for about an hour. Loosely cover cheesecake in a pan with plastic wrap. Refrigerate overnight.
To serve, remove ring from the springform pan. Slice cheesecake with a sharp knife dipped in hot water and wiped dry before each cut. Garnish individual servings with whipped cream and sugar pecans if desired.