Add the 1 1/2 cups chocolate chips and 2 tbsp butter to a large bowl.You can either melt it using a double boiler or by microwaving it. To Microwave start with one 30 second zap at full power then stir and do 20 seconds at 50% power, until mostly melted. For a double boiler place the bowl over a pot of simmering water and melt. The water should not touch the bowl.
Once the chocolate is mostly melted you can stir in the peanut butter. Mix until smooth.
Add in the salt and vanilla extract and mix. Allow the mixture to cool down a bit. More room temperature than hot, but not cool to the point of thickening back up.
Add about 6 cups or half a bag of Chex to a large bowl. Pour the chocolate mixture on top and add about two more cups of cereal on top. Gently mix together until all the cereal is coated. Add more cereal if you see unincorporated chocolate.
Now it's time to coat the cereal in powdered sugar. You can do this by adding cereal in batches to a sealable gallon-sized plastic bag with a cup of powdered sugar at the bottom and shaking until cereal is coated, adding more powdered sugar if needed. You can also do this in a large bowl. I love my puppy chow to be all individual pieces instead of clumps so I add the powdered sugar to a large bowl with the about half of the chocolate coated cereal. I add 1/2 cup of powdered sugar on top and use my clean hands to mix and separate. I bit messy but worth it!
Try using bittersweet chocolate in your next batch of puppy chow. You can go all on or half semi sweet. THere's a lot of sugar coating these pieces so a darker chocolate helps balance things out.This recipe calls for Chex but you can use Crispix or any generic cereal with a similar shape.Store in an a sealable plastic bag or other airtight container for up to a week at room temperature. Puppy Chow is RICH! I like to make a big batch and mix it with regular Chex cereal, corn flakes and some roasted peanuts for a slightly lighter party mix.