Prepare the crust: In a bowl, combine the graham cracker crumbs with melted butter. Mix until well combined and the crumbs hold together when pressed.
Form the base: Press the crumb mixture evenly into the bottom of a 9x13 inch baking dish to form a crust. Press down firmly to compact it.
Make the cream cheese layer: In a separate mixing bowl, beat the softened cream cheese, powdered sugar, and vanilla extract until creamy and smooth.
Spread cream cheese: Gently spread the cream cheese mixture over the graham cracker crust, smoothing it out into an even layer.
Prepare pumpkin layer: In another bowl, combine the pumpkin puree, pumpkin pie spice, and a pinch of salt. Fold in 1 ½ cups of whipped cream until fully incorporated.
Layer the pumpkin mixture: Spoon the pumpkin mixture evenly over the cream cheese layer, smoothing it out to cover completely.
Top with whipped cream: Finish the dessert by spreading the remaining whipped cream over the pumpkin layer. If desired, sprinkle chopped pecans over the top for added crunch.
Chill: Cover the dish with plastic wrap and refrigerate for at least 4 hours, or overnight for the best flavor and texture.
Serve: Before serving, dust the top with a light sprinkle of ground cinnamon and add extra whipped cream as desired.