In a small bowl combine the gingersnap crumbs and sugar. Stir in butter. Press onto the bottom and up the sides of a greased 9 inch deep dish pie plate. Bake at 350 degrees fro 8 -10 minutes or until lightly browned.
In a large mixing bowl, beat cream cheese until smooth. Gradually beat in sugar. Add the pumpkin, cinnamon, ginger, nutmeg and salt. Beat in eggs just until combined. Pour into crust. Bake for 35-40 minutes or until centre is almost set.
In a small bowl, combine the sour cream, sugar and vanilla. Spread over pie. Bake 8-12 minutes longer or until set . Cool on a wire rack. Cover and refrigerate for at least 4 hours. Sprinkle with cinnamon if desired.
Serves 8 - 10.