Preheat oven to 350 degrees F.
Place a stick of cold butter into a medium glass bowl and microwave for 1 minute.
Place 2 sleeves of graham crackers into a food processor or blender and turn into a fine crumb.
Add graham cracker crumbs, sugar, and pumpkin pie spice to melted butter and mix.
Press the mixture into the bottom of a 9x13" baking dish and poke with a fork so the crust stays flat while baking.
Bake for 10 minutes at 350 degrees F.
Add heavy whipping cream, maple syrup, and sugar to a bowl while the crust bakes.
Using a hand mixer at medium to high speed, whip the cream mixture for 3-5 minutes until soft peaks form. Set aside.
Add cream cheese, pumpkin puree, powdered sugar, and pumpkin pie spice to a bowl. Using a hand mixer at medium to high speed, whip the mixture until completely incorporated and fluffy.
Gently fold 2 cups of Maple Whipped Cream into the Pumpkin Fluff mixture and pour over the cooled Graham Cracker Crust.
Level out the pumpkin mixture and top with remaining whipped cream.
Add a sprinkle of pumpkin spice and chopped walnuts (optional), then chill in the refrigerator for at least 30 minutes to set.
Slice and enjoy!