Add the pudding mix and pumpkin pie spice to a large mixing bowl. Stir to combine.
Add the heavy cream pumpkin puree to the pudding mix. Use a hand mixer (or stand mixer) to beat everything together for 1-2 minutes until thick and smooth. Scrape the sides and bottom of the bowl periodically.
Transfer the pumpkin pie filling to the prepared graham cracker crust and spread it into an even layer.
Cover with plastic wrap and chill for 2-3 hours until set.
Remove the pie from the oven and uncover. Cut into 8 slices and top with whipped cream or Cool Whip if desired.
Notes
If you can't find French vanilla instant pudding, you can use regular vanilla or cheesecake flavor as a substitute.
Store any leftovers, covered, in the fridge for 3-4 days.