In a medium bowl, mix graham cracker crumbs, sugar, and melted butter until well blended. Press this mixture evenly into a 9-inch pie plate. Bake at 375°F for 6-7 minutes and let cool completely (about 1 hour).
Preheat the oven to 350°F.
Make the filling by mixing the pumpkin puree and sugar in a large bowl.
Add eggs, one at a time, making sure to mix well after each egg. Add sour cream and heavy cream and mix well.
Add pumpkin pie spice, vanilla, and salt. Mix until smooth.
Pour into graham cracker crust pie pan. Bake for 45 minutes, or until firm in the middle.
While the pie is baking, prepare Homemade Whipped Cream. To get started, place your mixing bowl and whisk attachment (or beaters if mixing with a hand mixer) in the freezer for about 10 minutes to chill.
Once chilled, remove from the freezer and add heavy whipping cream, powdered sugar, and vanilla to your bowl. Whether you are using the Kitchen-aid or a hand-mixer, start mixing on low speed then increase to medium-high and mix until soft peaks form.
Once the pie is done and cooled, top with homemade whipped cream and sprinkle with cinnamon or pumpkin pie spice right before serving.