Heat oven to 350 degrees. Stir together vanilla wafer crumbs, cocoa, powdered sugar and melted butter. Press mixture firmly onto bottom and 1/2-inch up side of 9-inch springform pan. Bake 8 minutes; cool slightly.
Increase oven temperature to 400 degrees. Beat cream cheese, sugar, flour and pumpkin pie spice in large bowl until well blended. Add pumpkin and eggs; beat until well blended. Stir in small chocolate chips; pour batter into prepared crust. Bake 10 minutes.
Reduce oven temperature to 250 degrees; continue baking 60 minutes or until almost set. Remove from oven to wire rack. With knife, loosen cake from side of pan. Cool completely; remove side of pan. Refrigerate about 5 hours before serving. Refrigerate any leftovers.