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