For the crust

• Preheat the oven to 350 degrees F and line a 9″ springform pan with parchment paper along the bottom and sides of the pan.
• Brown the butter and allow it to cool. To brown the butter, place it in a light colored saucepan over medium low heat. Melt it, then allow it to toast. The butter will first be loud – crackling and popping as the milk solids separate from the fat and the water evaporates. Then, the milk solids will start to toast and become golden brown. The butter will become quiet and foamy – that’s how you know it’s done.
• Once the browned butter is cooled, mix it with the crushed graham crackers, sugar, and cinnamon until well combined. 
• Press the crust into a thick even layer in the prepared pan. Use a flat bottomed glass or measuring cup and press firmly so that the crust holds together. 
• Bake at 350 for 12 minutes, then allow to cool completely while you make the cheesecake filling.

For the cheesecake

• Preheat the oven to 350 degrees F and place a baking dish filled with a couple inches of very hot water onto the bottom rack of the oven. Make sure there is also a rack in the center of the oven for the cheesecake to bake on.
• In the bowl of a stand mixer with the paddle attachment, beat the cream cheese on low speed for 5-7 minutes or until it is completely smooth. Make sure to wipe down the bottom and sides of the bowl to ensure everything gets combined and there’s no lumps remaining. 
• Add the sugar and mix on low for another 1-2 minutes or until well combined and smooth.
• With the mixer on the lowest speed, add the eggs and egg yolk one at a time. Make sure to stop the mixer to scrape the bowl as egg whites love to settle at the bottom of the bowl.
• Add the vanilla, sour cream, and cornstarch and mix until combined and smooth.
• Pour half of the batter into the cooled crust and gently spread into an even layer.
• Into the remaining batter, stir the pumpkin puree, cinnamon, nutmeg, and allspice. Fold gently until combined.
• Gently pour the pumpkin cheesecake layer on top of the vanilla layer, being careful not to let the layers mix. Use an offset spatula to spread the top into a smooth even layer. 
• Place the cheesecake onto the center rack and bake at 350 for 65-70 minutes, or until the cheesecake is set with a slightly wobbly center similar to jello.
• Once it’s done baking, leave the cheesecake in the oven, but turn it off and crack the door open about an inch. Leave it in there to begin cooling for an hour.
• Then, remove the cheesecake from the oven and place it on the counter to continue gradually cooling for another hour.
• Then, remove the walls of the springform pan and the parchment from the sides, and place the cheesecake in the fridge to cool completely overnight or AT LEAST 6 hours.

For the whipped cream topping

• When ready to serve the cheesecake, whip the heavy cream and vanilla in the bowl of a stand mixer with the whisk attachment until soft peaks form.
• Pile the whipped cream on top of the cheesecake and finish it off with a dusting of cinnamon.
• Alternatively, serve the whipped cream on the side!