Preheat oven to 325° F
Wrap the exterior of a greased 9″ springform pan in a double thickness of heavy-duty aluminum foil.
In a small bowl, combine cookie crumbs and pecans. Stir in butter. Press into the bottom and about an inch up the sides of the prepared pan. Bake at 325° F for 9-11 minutes, or until set. Cool on a wire rack.
In a large bowl, beat together cream cheese and 1/2 cup sugar until smooth. Beat in vanilla. Add eggs; beat on low speed until combined.
Place pumpkin purée in a small bowl and stir in cinnamon, nutmeg, and remaining sugar.
Remove 3/4 cup pumpkin filling and set aside.
Pour remaining pumpkin filling into the crust; top with cream cheese mixture. Drop reserved pumpkin filling by spoonfuls over top and cut through filling with a knife to swirl.
Place springform pan in a large baking pan; add 1 cup of hot water to larger pan. Bake for 50-60 minutes, or until center is just set and top appears dull.
Remove the springform pan from the water bath. Cool on a wire rack for 10 minutes. Carefully run a knife around edge of pan to loosen; cool 1 hour longer. Refrigerate overnight. Remove sides of pan.
Garnish with whipped topping, pecan halves, and gingersnap cookie wedges, if desired.