Position a rack in the center of the oven and heat the oven to 325°F.
Pulse the gingersnaps in a blender or food processor until fine. In a medium bowl, mix the crumbs and melted butter until evenly moistened.
Put the crumbs in the tart pan and use your hands to spread the crumbs so that they cover the bottom of the pan and sides. Using your fingers, pinch and press some crumbs around the inside edge of the pan, covering the sides evenly in a 1/4 inch thick wall.
Spread the remaining crumbs evenly over the bottom of the pan and press firmly.
Bake the crust 8-10 minutes, then remove to a wire rack.
While the crust is cooling, Add the cream cheese, brown sugar, melted white chocolate, and pumpkin spice in a medium bowl. Use a hand mixer (or stand mixer) to blend the ingredients together until smooth, 3-4 minutes.
Add the pumpkin puree and mix until combined. Add each egg one at a time, mixing well between, until the mixture is smooth and evenly blended.
Pour the cheesecake mixture into the cooled tart crust, spreading it with a spatula to even it out. Bake at 325°F for 30-35 minutes, or until filling is just set. Transfer tart pan to a wire rack to cool completely.
When ready to serve, top with whipped cream and garnish as desired with extra gingersnaps and/or white chocolate.