Preheat oven to 325° and grease a 7x11 or a 9x13 pan.
In a food processor, pulse the vanilla wafers and butter together until it's well combined. Press into the bottom of the pan and place in fridge while you prepare the filling.
In the bowl of a stand mixer with a paddle attachment, beat the cream cheese until it's fluffy and smooth. About 2 minutes. Scrape down the sides with a spatula. Then add the sugar, vanilla and eggs and mix until combined. Pour half of this mixture over the cooled crust and then place in the freezer for about 20 minutes, until it's starting to firm up a little bit.
To the remaining cheesecake mixture, add the pumpkin puree and pumpkin pie spice. Mix until combine, scraping down sides if needed. Pour this over the plain cheesecake. If using a 7x11, bake for 40 minutes. If using a 9x13, bake for 30 minutes. While this bakes, make your crumble topping.
In a medium bowl combine all crumble toppings using your fingers until it forms together. When the cheesecake comes out, crumble this over the top evenly.
If using a 7x11, bake for another 40 minutes. If using a 9x13, bake for another 30 minutes. Or until knife comes out clean. Cool at room temp for 30 minutes. Then transfer to the fridge for at least an hour. Cut into bars and enjoy! Good in a sealed container in the refrigerator up to 5 days.