Heat oven to 325 degrees. Combine graham cracker crumbs, gingersnap cookie crumbs, 1 tablespoon granulated sugar and butter. Press into a 9-inch springform pan. Bake crust 8 to 10 minutes. Cool completely.

In a large bowl, beat cream cheese, brown sugar and 1/2 cup granulated sugar until smooth and creamy; mix in flour. Add pumpkin and pumpkin pie spice, mixing until just smooth. Add eggs, one at a time, until just blended.

Place springform pan on baking sheet. Pour cheesecake mixture over crust. Bake 1 hour, 15 minutes or until set but center still jiggles.

Meanwhile, combine sour cream, vanilla and remaining 1/4 cup granulated sugar. Spread over the top of the baked cheesecake. Return cheesecake to oven for 8 minutes to set the topping.

Cool completely. Cover and refrigerate until firm.