Add the thawed 8-ounce package of whipped topping (like Cool Whip), 15-ounces of canned pumpkin puree, and 2 teaspoons pumpkin pie spice to a large mixing bowl.
Empty the dry contents of the 3.4-ounce package of Instant Vanilla Pudding into a mixing bowl and stir until well combined.
Stir in 1-1/2 cups mini marshmallows until they are evenly distributed throughout the pumpkin fluff dip.
Serve in a bowl alongside graham crackers, Gingersnaps, or apple slices for dipping.
Add a dollop of whipped topping on top of the Pumpkin Fluff and sprinkle with cinnamon just before serving for a nice presentation.