Begin by lining a baking sheet with parchment paper and set aside.
In a microwave-safe bowl, combine the semi-sweet chocolate chips and creamy peanut butter. Microwave on high for 30 seconds, remove and stir. If necessary, microwave for an additional 15 seconds until melted and smooth.
Stir in the vanilla extract and a pinch of salt into the melted chocolate mixture.
In a large mixing bowl, add the Rice Chex cereal. Pour the chocolate-peanut butter mixture over the cereal and gently fold until all pieces are evenly coated.
In a separate small bowl, mix the cocoa powder, powdered sugar, and brown sugar.
Transfer the chocolate-coated cereal into a large zip-top bag or container. Add the cocoa powder mixture and shake well until the cereal is evenly coated with the sugar mixture.
Spread the coated puppy chow onto the prepared baking sheet to let it cool and harden for about 10 minutes.
Once cooled, break into pieces and store in an airtight container.