Measure the Chex cereal into a large mixing bowl and set aside.
In a microwave-safe bowl, combine the chocolate chips and butter. Microwave in 30-second intervals, stirring between each, until completely melted and smooth, about 1-2 minutes total.
Stir the vanilla extract into the melted chocolate mixture until combined.
Pour the chocolate mixture over the cereal and gently fold with a spatula until every piece is evenly coated.
Drizzle the salted caramel sauce over the chocolate-coated cereal in a thin stream, tossing gently as you go to create ribbons throughout.
Let the mixture cool for 2-3 minutes, then transfer to a large resealable plastic bag or container with a lid.
Add the powdered sugar to the bag, seal tightly, and shake vigorously for 1-2 minutes until all pieces are evenly coated in a white, snowy layer.
Spread the puppy chow on a large sheet of parchment paper and sprinkle with flaky sea salt. Let it air-dry for 10 minutes before serving or storing.
