01 - Line a large baking sheet with parchment or wax paper and set aside.
02 - Place the rice cereal squares in a large mixing bowl.
03 - In a microwave-safe bowl, combine white chocolate chips and butter. Microwave in 30-second intervals, stirring between each, until smooth and fully melted (about 1 to 1 1/2 minutes total).
04 - Stir in lemon juice and lemon zest until fully incorporated.
05 - Pour the melted mixture over the cereal. Gently fold with a spatula until all pieces are evenly coated.
06 - In a large zip-top bag, combine powdered sugar and instant lemonade mix.
07 - Add the coated cereal to the bag. Seal and shake vigorously until all pieces are well-coated.
08 - Spread the puppy chow onto the prepared baking sheet to cool and set for about 10 minutes before serving.