Melt white chocolate by putting it in a microwave safe bowl, and heating on 50% power for 30 seconds. Stir after 30 seconds, and repeat until chocolate is melted.
Pour chocolate over the Chex Cereal, zip bag up and shake to combine.
Add powdered sugar into the bag, and shake to coat.
Pour Chex mixture into a very large mixing bowl.
Add the rest of the snack mix ingredients to the bowl, and toss together, being careful not to break the cereal pieces or pretzels.