You can heat treat cake mix it before starting the recipe if you’re concerned about the raw flour within it. Spread the cake mix in an even layer on a baking sheet and bake at 350F for 5 minutes. Let it cool completely.
Add the Chex cereal to a large bowl. Melt the white chocolate in a double boiler, stirring regularly until smooth.
Pour melted chocolate on the Chex, then carefully mix with a spatula until covered as much as you can.
Add in 3 ounces of sprinkles (in batches), I like the rainbow non-peril ones, because they are small and colorful.
Mix as well as you can then transfer to a large resealable bag, then add in cake mix and icing sugar. Add more icing sugar as needed to make sure all the chocolate is covered.
Seal the bag and gently toss it all around to coat, then transfer to a large baking sheet and allow it to set.
Notes
Heat Treat the Cake Mix: Dry cake mix contains raw flour, so heat treat it before adding it to the puppy chow.
Work While the Coating Is Wet: Add the sprinkles before the candy coating sets so they stick to the cereal.
Fold Gently: Use a rubber spatula and a light hand to avoid crushing the Chex cereal.
Add Powdered Sugar as Needed: If some of the melted coating is still exposed after shaking, add a little more powdered sugar and toss again.
Let the Cake Mix Cool: If you heat treat your cake mix, make sure it has returned to room temperature before starting. You do not want it to be warm when adding it to the bag.
Room Temperature: Once set, store in an airtight container at room temperature for up to 1 week, or refrigerate for up to 2 weeks.
Freezer: Freeze in an airtight container or freezer bag for longer storage. Let it come to room temperature before serving.