01 - Line a large baking sheet with parchment or wax paper and set aside for later use.
02 - Pour the rice cereal squares into a large mixing bowl, ensuring plenty of space for coating.
03 - Combine white chocolate chips and butter in a microwave-safe bowl. Microwave in 30-second intervals, stirring thoroughly between each interval, until completely smooth and melted, approximately 1 to 1 1/2 minutes total.
04 - Stir fresh lemon juice and lemon zest into the melted chocolate mixture until fully incorporated.
05 - Pour the melted lemon-white chocolate mixture over the cereal. Gently fold with a spatula, ensuring all cereal pieces are evenly coated with the mixture.
06 - In a large zip-top bag, combine powdered sugar and instant lemonade drink mix. Seal and shake to blend evenly.
07 - Add the coated cereal to the bag with the powdered mixture. Seal tightly and shake vigorously until all cereal pieces are thoroughly coated with the lemon-sugar blend.
08 - Spread the completed puppy chow onto the prepared baking sheet in an even layer. Allow to cool and set for approximately 10 minutes before serving.
09 - Transfer to an airtight container and store at room temperature for up to 5 days for optimal freshness.