Pulse graham crackers in a food processor until fine crumbs form, about 15-20 seconds. Blend in sugar and cinnamon, pour in melted butter, and stir until well combined. Firmly press into a 9-inch pie plate and chill for 10-15 minutes.

In a large mixing bowl, combine pumpkin puree, vanilla pudding mix, and pumpkin pie spice. Mix on medium speed for 2-3 minutes until smooth and thick.

Gently fold in whipped topping to the pumpkin mixture using a rubber spatula.

Spread the filling into the chilled graham cracker crust and smooth the top gently. Cover with plastic wrap and let chill for at least 4 hours.

Slice the pie with a sharp, serrated knife. Serve chilled, optionally topped with extra whipped topping and a sprinkle of cinnamon or nutmeg.