Preheat oven to 350F.
Prepare the pan for the water bath. Wrap the outside of a 9 inch springform pan with two layers of heavy duty aluminum foil. Grease the bottom and sides of the springform pan.
Place gingersnaps in a food processor and pulse until the cookies resemble fine crumbs. Transfer gingersnap crumbs to a medium size bowl.
Melt butter in the microwave or on the stovetop. Add melted butter to gingersnap crumbs and mix with a fork until well combined.
Transfer gingersnap mixture to the bottom of the springform pan. Use your hands or the bottom of a measuring cup to firmly press the mixture down and partially up the sides of the pan.
Bake for 10 minutes. Remove from oven and set aside to cool.
Set oven temperature to 325F. In a large bowl, combine cream cheese, brown sugar, eggs, canned pumpkin, sour cream, pumpkin pie spice, cinnamon, vanilla and flour.
Use an electric mixer to beat until well combined. Use a spatula to scrape down the sides of the bowl as necessary. There shouldn't be any lumps in the batter.
Pour mixture on top of cooled gingersnap crust. Smooth the top with the back of a spoon.
Prepare the water bath. Place the cheesecake into a pan big enough to allow the springform pan to sit flat. Pour hot water into the pan. The water should be about one inch up the side of the springform pan.
Bake cheesecake for 1.5 hours. Do not open the oven while the cheesecake is baking. Turn the oven off and allow the cheesecake to sit in the oven for another hour.
Remove cheesecake from oven and let it rest on the counter until it comes to room temperature. Cover with plastic wrap.
Transfer cheesecake to the fridge and let sit overnight. Top with whipped cream and drizzle with caramel sauce if desired. Use a knife to cut cheesecake into slices. Makes 16 slices.