Measure the cereal into a large mixing bowl and set aside. Line a large baking sheet with parchment paper.
Combine white chocolate chips and butter in a microwave-safe bowl. Microwave in 30-second intervals, stirring thoroughly between each, until completely melted and smooth (about 90 seconds total).
Pour the melted white chocolate mixture over the cereal and gently fold with a rubber spatula until every piece is evenly coated.
Let the coated cereal cool for 2-3 minutes, then transfer to a large resealable plastic bag or container with a lid.
Add the sifted powdered sugar, seal the bag, and shake vigorously for 30-60 seconds until all pieces are covered in a snowy white coating.
Spread the coated cereal on the prepared baking sheet in a single layer. Sprinkle the freeze-dried blueberries over the top and gently toss to distribute.
Allow the mix to cool completely for about 10 minutes before serving or storing. Break apart any large clumps with your hands.
