Preheat your oven to 350°F (175°C). In a mixing bowl, combine the graham cracker crumbs, granulated sugar, melted butter, and optional cinnamon until well blended. Transfer to a 9-inch springform pan, pressing it firmly into the bottom and up the sides. Bake for 10 minutes and cool.

Reduce the oven temperature to 325°F (163°C). In a large bowl, beat the cream cheese and granulated sugar until smooth. Gradually add pumpkin puree, vanilla extract, and pumpkin pie spice, mixing until incorporated. Add eggs one at a time, blending each before next, then fold in heavy cream.

Wrap the springform pan in foil and place it in a larger roasting pan. Fill the roasting pan with hot water halfway up the sides of the springform pan. Bake for 55-65 minutes until edges are set and center jiggles slightly.

Turn off the oven and crack the door open. Allow the cheesecake to cool inside for 1 hour. Remove from the water bath and foil. Transfer to a cooling rack to cool to room temperature, then refrigerate for at least 4 hours, ideally overnight.

For the topping, beat heavy cream, powdered sugar, and vanilla extract until stiff peaks form. Spread or pipe whipped cream over the cheesecake and dust with cinnamon before serving.