1. 1. Measure the Chex cereal into a very large bowl.

2. 2. Next, combine chocolate chips, peanut butter, and butter in a microwave-safe bowl.

3. 3. Heat this mixture in the microwave for 60 seconds. Stir well.

4. 4. Continue heating in 30-second intervals, stirring after each, until smooth and fully melted. This usually takes 1.5 to 2 minutes total.

5. 5. Stir in the vanilla extract.

6. 6. Pour the melted chocolate mixture over the Chex cereal.

7. 7. Gently stir with a rubber spatula until all the cereal pieces are evenly coated.

8. 8. Combine the powdered sugar and pumpkin spice (if using) in a large, clean gallon-sized Ziploc bag.

9. 9. Add half of the coated cereal to the bag.

10. 10. Seal the bag, making sure to remove most of the air.

11. 11. Shake vigorously until the cereal is completely coated in the powdered sugar.

12. 12. Remove the coated Harvest Puppy Chow to a clean baking sheet lined with parchment paper.

13. 13. Repeat with the remaining half of the coated cereal.

14. 14. Allow the Harvest Puppy Chow to cool and set for at least 15 minutes before serving. Enjoy your delicious Harvest Puppy Chow!