1. Stir together the graham cracker crumbs, melted butter, and granulated sugar in a medium bowl until the mixture looks like wet sand.

2. Press the crust mixture firmly into the bottom of a 9-inch springform pan or pie dish, then refrigerate while preparing the filling.

3. In a large bowl, beat the softened cream cheese until smooth and fluffy.

4. Add the pumpkin puree, 3/4 cup powdered sugar, vanilla extract, pumpkin pie spice, and cinnamon, then beat until fully combined.

5. In a separate bowl, whip the cold heavy cream with 2 tablespoons powdered sugar until stiff peaks form.

6. Gently fold the whipped cream into the pumpkin mixture in batches until the filling is light and smooth.

7. Spoon the filling over the chilled crust and smooth the top evenly.

8. Cover and refrigerate for at least 6 hours or overnight until fully set.

9. Top with whipped cream, cinnamon or pumpkin pie spice, and crushed graham crackers or chopped pecans before serving, if desired.