Pour the Chex cereal into a medium bowl.
Melt the white chocolate chips in 25-second increments at 50% power in a microwave-safe bowl, stirring well in between. When most of the white chocolate is melted, just keep stirring to melt the rest so as not to overheat it. Stir in 1 ½ teaspoons of cinnamon into the melted white chocolate.
Pour the mixture over the Chex cereal and stir until the cereal is evenly coated.
Pour powdered sugar and the rest of the cinnamon into a gallon-sized plastic bag. Transfer the cereal mixture into the bag and toss until evenly coated.
Transfer back to a bowl and dig in, allowing to cool for about 15 minutes before serving.