Prepare the Coating: In a microwave-safe bowl, melt the white chocolate chips and butter in 20-second intervals, stirring after each until smooth. Once melted, mix in the vanilla extract.
Coat the Cereal: Place the rice cereal squares in a large mixing bowl and pour the melted white chocolate mixture over them. Gently stir until all pieces are evenly coated.
Mix the Dry Ingredients: In a separate bowl, combine the powdered sugar, vanilla cake mix, and crushed freeze-dried strawberries.
Toss to Coat: Transfer the coated cereal into a large zip-top bag or a container with a tight lid. Add the powdered sugar mixture, seal the bag, and shake well until the cereal is fully coated.
Cool and Serve: Spread the coated cereal on a baking sheet lined with parchment paper. Let it sit until completely dry before serving. Store in an airtight container for up to a week.