In a large double boiler melt the coconut oil, chocolate chips, and peanut butter. Mix well and then fold in the pumpkin puree until smooth. Add the vanilla and 2 teaspoons of the pumpkin pie spice. At this point I recommend tasting the mixture. If you still want it more-spiced add the additional spice a little at a time until it has the flavor you want.
Take the top bowl/pot off the double boiler and carefully fold in the cereal, 1 cup at a time. Once all of the cereal is coated transfer to a 2 gallon zip-top bag. Add half of the powdered sugar to the bag, seal, and shake to coat. Let the cereal cool for about 15-20 minutes and then repeat with the remainder of the powdered sugar.