In a medium (chilled) bowl, add the heavy whipping cream and sugar. Using the hand mixer, beat the whipped cream and sugar on medium speed until stiff peaks form. This can take 1 - 2 minutes. Don't overbeat.
NOTE: If you want to make additional whipped cream for topping, double the heavy whipping cream to four cups and the sugar to one cup. Mix like above and then remove half of the mixture from the bowl and set aside for serving.
Add the cream cheese, pumpkin, pie spice, and vanilla extract. Mix until just combined using a spatula or the hand mixer on low speed.
Fold in the white chocolate chips.
Break up the graham crackers to cover the bottom of your springform pan. Start with large pieces and then go around the edges with smaller pieces. My photo should help illustrate . . . you can't mess up an icebox cake.
Spread 1/3 of your pumpkin mixture on top of the graham crackers. Place more graham crackers on top then repeat. You're going to have three layers of graham cracker and three layers of pumpkin mixture, with the top being pumpkin.
Stick in the fridge and chill for at least four hours.
Serve your icebox cake garnished with whipped cream and cinnamon if you like!
Nutritional information does not include whipped cream for topping, as it is optional.